source: doc/manual.lyx@ e40e335

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\author "Jan H. Meinke" 
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\begin_body

\begin_layout Title

\size huge
SMMP v.
 3
\end_layout

\begin_layout Author
F.
 Eisenmenger
\end_layout

\begin_layout Author Email
eisenmenger@fmp-berlin.de
\end_layout

\begin_layout Affiliation
Leibniz-Institut f
\begin_inset ERT
status inlined

\begin_layout Standard

{
\backslash
"u}
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r Molekulare Pharmakologie, 13125 Berlin, Germany
\end_layout

\begin_layout Author
U.H.E.
 Hansmann
\end_layout

\begin_layout Author Email
hansmann@mtu.edu
\end_layout

\begin_layout Affiliation
Michigan Technological University, Houghton, MI 49931-1291, USA
\end_layout

\begin_layout Affiliation
Computational Biology and Biophysics, NIC, 52428 J
\begin_inset ERT
status inlined

\begin_layout Standard

{
\backslash
"u}
\end_layout

\end_inset

lich, Germany
\end_layout

\begin_layout Author
Sh.
 Hayryan
\end_layout

\begin_layout Author Email
shura@phys.sinica.edu.tw
\end_layout

\begin_layout Author
C.-K.
 Hu
\end_layout

\begin_layout Author Email
huck@phys.sinica.edu.tw
\end_layout

\begin_layout Affiliation
Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
\end_layout

\begin_layout Author
J.
 H.
 Meinke
\end_layout

\begin_layout Author Email
j.meinke@fz-juelich.de
\end_layout

\begin_layout Affiliation
Computational Biology and Biophysics, NIC, 52428 J
\begin_inset ERT
status inlined

\begin_layout Standard

{
\backslash
"u}
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lich, Germany
\end_layout

\begin_layout Author
S.
 Mohanty
\end_layout

\begin_layout Author Email
s.mohanty@fz-juelich.de
\end_layout

\begin_layout Affiliation
Computational Biology and Biophysics, NIC, 52428 J
\begin_inset ERT
status inlined

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{
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"u}
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lich, Germany
\end_layout

\begin_layout Standard
\noindent
\begin_inset LatexCommand tableofcontents

\end_inset


\end_layout

\begin_layout Section
Introduction
\end_layout

\begin_layout Standard
The SMMP (
\series bold
S
\series default
imple 
\series bold
M
\series default
olecular 
\series bold
M
\series default
echanics for 
\series bold
P
\series default
roteins) package is designed for molecular simulations of linear proteins
 within the standard geometry model.
 The package contains various modern Monte Carlo algorithms and energy minimizat
ion routines.
 The energy of a protein can be calculated by exploiting one of four force
 fields: ECEPP/2, ECEPP/3 
\begin_inset LatexCommand citep
key "ECEPP3"

\end_inset

, FLEX or Lund.
 Two subroutines for approximating protein-solvent interactions by means
 of calculating the solvent accessible surface area of atomic groups are
 included.
 Nine sets of solvation parameters are available.
 All calculations are done with double precision, but the user can easily
 modify this option by changing the corresponding IMPLICIT statement.
\end_layout

\begin_layout Standard
This manual provides the user with the necessary information for installation
 of the program, the format of the input and output files, a brief description
 of the important routines, and describes some limitations of the package.
 A few example runs providing detailed explanation of input and output are
 added.
 More information on SMMP, definitions, background and references for force
 fields and algorithms as used in the program package can be found in 
\begin_inset LatexCommand citep
key "Eisenmenger2001,Eisenmenger2006"

\end_inset

.
\end_layout

\begin_layout Standard
SMMP is offered as Open Source.
 The program is written in standard FORTRAN.
 We encourage users to improve the code and add their own modules.
 Please send us your modifications and additions, so we can add them to
 future releases.
 Or send us a note and let us know where users can download your modules.
 The usage and distribution of the program are governed by the following
 license agreement:
\newline
 
\end_layout

\begin_layout Quote
SMMP is free software; it can be used, modified, and redistributed under
 the terms of the GNU General Public License version 2 (
\shape italic
http://www.gnu.org/licenses/gpl.html
\shape default
) as published by the Free Software Foundation, EXCEPT WHERE RESTRICTED
 BY ONE OF THE FOLLOWING CLAUSES.
 
\newline
SMMP shall not be used for commercial or military purposes.
 The authors request notification if parts of SMMP are incorporated in other
 programs.
\newline
The use of SMMP has to be acknowledged in all resulting publications
 by quoting: 
\shape italic
F.
 Eisenmenger, U.H.E.
 Hansmann, S.
 Hayryan and C.K.
 Hu,
\shape default
 
\series bold
[SMMP] A Modern Package for Protein Simulations
\series default
, 
\shape italic
Comp.
 Phys.
 Comm.
 138 (2001) 192-212
\shape default
; 
\series bold
An Enhanced Version of SMMP - Open-Source Software Package for Simulation
 of Proteins
\series default
, 
\shape italic
Comp.
 Phys.
 Comm.
 174 (2006) 422-
\shape default
429.
 
\emph on
J.
 H.
 Meinke, S.
 Mohanty, F.
 Eisenmenger and U.H.E.
 Hansmann,
\series bold
\emph default
 SMMP v.
 3.0 --- Simulating proteins and protein interactions in Python and Fortran
\series default
, submitted to 
\emph on
Comp.\InsetSpace ~
Phys.\InsetSpace ~
Comm.
\emph default

\newline
 SMMP is distributed in the hope that it will be useful, but WITHOUT ANY
 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 FOR A PARTICULAR PURPOSE.
 See the GNU General Public License for more details.
 
\end_layout

\begin_layout Standard
\noindent
The most recent version of SMMP can be found on the program package's web
 sites: 
\series bold
http://www.smmp05.net
\series default
 or 
\series bold
http://www.phy.mtu.edu/biophys/smmp.htm
\series default
.
 Any suggestions for improvements of the code or reports on bugs are welcome.
 Please send your remarks to the authors.
\end_layout

\begin_layout Standard
\noindent

\series bold
Acknowledgments:
\series default

\newline
 U.H.
 acknowledges support by a research grant (CHE-9981874) of the National
 Science Foundation (USA).
 S.H.
 and C.K.H.
 are supported by Academia Sinica (Taipei) and by the National Science Council
 of the Republic of China (Taiwan) under Contract No.
 NSC 89-2112-M-001-084.
 
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\begin_layout Standard


\backslash
newpage
\end_layout

\begin_layout Standard

\end_layout

\end_inset


\end_layout

\begin_layout Section
Changes from Previous Version
\end_layout

\begin_layout Subsection
New Features
\end_layout

\begin_layout Subsubsection
New Force Field
\end_layout

\begin_layout Paragraph
Lund Force Field
\end_layout

\begin_layout Standard
The Lund force fields is a fast force field that uses a minimal set of parameter
s to obtain good folding statistics.
 It has been used successfully for protein folding, unfolding, and aggregation
 simulations.
 For details see 
\begin_inset LatexCommand citep
key "Irback2005"

\end_inset

.
\end_layout

\begin_layout Subsubsection
Multi-molecule simulations
\end_layout

\begin_layout Standard
SMMP 3.0 implements inter-molecular interactions based on the ECEPP/3 force
 field.
\end_layout

\begin_layout Subsubsection
Biased Gaussian Step
\end_layout

\begin_layout Standard
A new Monte Carlo move that interpolates smoothly between two nearly fixed
 end points.
\end_layout

\begin_layout Subsubsection
Parallel energy calculation
\end_layout

\begin_layout Standard
The energy calculation for the ECEPP/3 force field can now be done in parallel
 making it possible to speed up simulations for serial algorithms.
 Combining the parallel energy calculation with parallel tempering, SMMP
 can be used efficiently on 2048 processors on an IBM BlueGene/L super computer.
\end_layout

\begin_layout Subsubsection
Python bindings
\end_layout

\begin_layout Standard
We now provide Python bindings to SMMP that make the data structure and
 algorithms available from (interactive) Python scripts.
 
\end_layout

\begin_layout Subsection
API Changes
\end_layout

\begin_layout Standard
In previous versions of SMMP the parameters for each algorithm were given
 in the source code of the algorithm using PARAMETER statements.
 Now, the parameters are passed as function arguments making the program
 much more flexible.
 The following functions and subroutines now have a different signature:
 anneal, canon, minim, mulcan_par, mulcan_sim, outpdb, outvar, partem_p,
 and regul.
 For details see Section\InsetSpace ~

\begin_inset LatexCommand ref
reference "sec:Frequently-used-Functions"

\end_inset

.
 
\end_layout

\begin_layout Section
Installation
\end_layout

\begin_layout Standard
SMMP requires a FORTRAN 90 compatbile compiler.
 We have compiled it using gfortran, pgif, xlf, and ifort on various platforms.
 It should compile and link on any platform with a contemporary FORTRAN
 compiler.
 All subroutines are stored in *.f or *.f90 files.An example Makefile is included
 in the package.
 There are no machine dependent routines included in SMMP.
 All COMMON blocks and the limiting parameters are gathered in INCL.H, which
 is attached to the necessary modules through an INCLUDE statement.
 After uncompressing and unpacking (via 'tar -xvf' command) the SMMP package
 into a separate directory For the installation of SMMP the user needs to
 run 
\family typewriter
make
\family default
 in the directory with the source code.
 You should edit the Makefile to customize the compiler command and compiler
 options used.
 
\end_layout

\begin_layout Subsection
Building pySMMP
\end_layout

\begin_layout Standard
This version of SMMP includes Python bindings to SMMP.
 To build them, you need f2py, which is part of the numpy package.
 If f2py is already installed on your system, pySMMP is built by issuing
 the command 
\emph on
make pybind
\emph default
.
 
\end_layout

\begin_layout Standard
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\begin_layout Standard


\backslash
newpage
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

\end_layout

\end_inset


\end_layout

\begin_layout Section

\emph on
\noun on
Biased Gaussian Steps
\end_layout

\begin_layout Subsection
Introduction
\end_layout

\begin_layout Standard
The Bias Gaussian Step, BGS for short, is a semi-local conformational update,
 involving a concerted rotation of the backbone angles of 4 consecutive
 residues in the protein chain.
 The upstream part of the protein backbone, 
\begin_inset Quotes eld
\end_inset

before
\begin_inset Quotes erd
\end_inset

 the first of the 4 residues used for BGS is left unchanged.
 The downstream part, 
\begin_inset Quotes eld
\end_inset

after
\begin_inset Quotes erd
\end_inset

 those 4 residues is moved slightly as a rigid body.
 The section containing the 4 BGS residues is locally deformed.
 
\end_layout

\begin_layout Subsection
Parameters
\end_layout

\begin_layout Standard
The increments to the backbone angles involved in the update are first chosen
 from a Gaussian distribution, and then biased to impart minimal changes
 to the downstream parts of the chain.
 If this later 
\begin_inset Quotes eld
\end_inset

locality
\begin_inset Quotes erd
\end_inset

 condition is relaxed, they would be trivially Gaussian-distributed.
 There are two parameters of relevance, called 
\begin_inset ERT
status open

\begin_layout Standard

$a_{
\backslash
mathrm{BGS}}$
\end_layout

\end_inset

 and 
\begin_inset ERT
status open

\begin_layout Standard

$b_{
\backslash
mathrm{BGS}}$
\end_layout

\end_inset

, declared in the common block 
\noun on
bgs_r
\noun default
.
 
\begin_inset ERT
status open

\begin_layout Standard

$a_{
\backslash
mathrm{BGS}}$
\end_layout

\end_inset

 controls the size of the increments, and hence directly influences the
 acceptance rate of the updates.
 Smaller the value of 
\begin_inset ERT
status open

\begin_layout Standard

$a_{
\backslash
mathrm{BGS}}$
\end_layout

\end_inset

, smaller the increments, and hence greater the chances of the update being
 accepted.
 Since a trivial zero size update is of little practical interest, even
 if it is always accepted, it is desirable to have the value of 
\begin_inset ERT
status open

\begin_layout Standard

$a_{
\backslash
mathrm{BGS}}$
\end_layout

\end_inset

 as large as possible.
 
\begin_inset ERT
status open

\begin_layout Standard

$b_{
\backslash
mathrm{BGS}}$
\end_layout

\end_inset

 controls the degree of locality of the update, i.e., to what extent the downstrea
m parts should be allowed to move.
 Larger 
\begin_inset ERT
status open

\begin_layout Standard

$b_{
\backslash
mathrm{BGS}}$
\end_layout

\end_inset

 means a stricter locality criterion, and smaller acceptance.
 These two parameters should not be arbitrarily changed.
 The default values in SMMP, 
\begin_inset ERT
status open

\begin_layout Standard

$a_{
\backslash
mathrm{BGS}}=300$
\end_layout

\end_inset

 and 
\begin_inset ERT
status open

\begin_layout Standard

$b_{
\backslash
mathrm{BGS}}=10$
\end_layout

\end_inset

 are tuned, to ensure maximum acceptance at a reasonable update size and
 locality constraint.
 
\end_layout

\begin_layout Subsection
Detailed balance and BGS
\end_layout

\begin_layout Standard
Information about the current state of the protein is used inside BGS to
 bias the increments towards greater locality.
 Thus the current conformation affects the distribution of the incremental
 angles.
 This means that the reverse update would have a different probability of
 being proposed.
 Because of this, in order to ensure detail balance, an extra multiplicative
 weight factor is needed for BGS along with the standard Metropolis weight,
 to decide whether an update should be accepted.
 The implementation of BGS in SMMP calculates this weight and evaluates
 whether or not the proposed update was accepted.
 
\end_layout

\begin_layout Subsection
The function BGS in SMMP
\end_layout

\begin_layout Standard
BGS is implemented in SMMP as a function with the following signature:
\end_layout

\begin_layout Standard
integer function bgs(eol1,dummy)
\end_layout

\begin_layout Standard
The parameter eol1 passed to BGS is the energy of the system before the
 call.
 The argument 
\begin_inset Quotes eld
\end_inset

dummy
\begin_inset Quotes erd
\end_inset

 is a function that calculates the exponent of the Metropolis weight function.
 The return value is 1 for an accepted BGS move and 0 for a rejected move.
 
\end_layout

\begin_layout Subsubsection
Using BGS in SMMP
\end_layout

\begin_layout Standard
To use BGS, one must ensure that the subroutine init_lund, which initialises
 several arrays used in BGS, is called during the initialisation phase of
 the program.
 These arrays store information about the BGS-capable angles in the protein
 chain.
 Therefore, init_lund should be called again, in case the program changes
 the amino acid sequence of a molecule or the total number of molecules
 in the system.
 
\end_layout

\begin_layout Standard
The global switch 
\noun on
upchswitch
\noun default
 controls how BGS is used by the metropolis subroutine, which is normally
 the routine that calls BGS.
 For 
\noun on
upchswitch=0, BGS 
\noun default
is never used.
 For 
\noun on
upchswitch=1, 
\noun default
it is used with a probabilty 
\noun on
bgsprob
\noun default
, which is another global parameter.
 For 
\noun on
upchswitch=2, 
\noun default
BGS is used when possible with a temperature dependent probability.
 At higher temperatures abrupt single angle changes are more effective in
 browsing the conformation space quickly.
 A local update like BGS should therefore have a small probability at high
 temperatures.
 At low temperatures, often the system is in a compact state with significant
 secondary structure, and it is desirable to explore the neighbourhood of
 that state to refine the structure.
 BGS is more efficient at this compared to single angle updates, and hence
 should have a higher probability at lower temperatures.
 The choice, 
\noun on
upchswitch=2 
\noun default
uses this scheme for BGS use.
 
\end_layout

\begin_layout Section
Getting Started
\end_layout

\begin_layout Standard
The quickest way to get started is to use one of the examples in the EXAMPLES
 directory as a template.
 The examples are described in Section\InsetSpace ~

\begin_inset LatexCommand ref
reference "sec:Examples"

\end_inset

.
\end_layout

\begin_layout Standard
SMMP does not include an interpretor of user-defined commands instead the
 preparation of a simulation is done in the MAIN module calling corresponding
 simulation subroutine(s).
 After adjusting MAIN to your needs, SMMP has to be re-compiled.
 We provide a sample main file with detailed comments.
 For a comment-free version see Listing 
\begin_inset LatexCommand ref
reference "listing:mainmc"

\end_inset

.
 
\end_layout

\begin_layout Standard
\begin_inset listings
lstparams "float=h,language=Fortran,numbers=left"
inline false
status open

\begin_layout Standard

      program main
\end_layout

\begin_layout Standard

      include "../INCL.H"
\end_layout

\begin_layout Standard

     
\end_layout

\begin_layout Standard

      character*80 libdir, seqfile, varfile
\end_layout

\begin_layout Standard

      character grpn*4,grpc*4       
\end_layout

\begin_layout Standard

      integer nequi, nsweeps, nmes       
\end_layout

\begin_layout Standard

      double precision tmax, tmin       
\end_layout

\begin_layout Standard

      logical lrand 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

      libdir = '../SMMP/'
\end_layout

\begin_layout Standard

      ientyp = 0       
\end_layout

\begin_layout Standard

      sh2 = .true.
          
\end_layout

\begin_layout Standard

      itysol = 0
\end_layout

\begin_layout Standard

      call init_energy(libdir)
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

      grpn = 'nh2'
\end_layout

\begin_layout Standard

      grpc = 'cooh'
\end_layout

\begin_layout Standard

      iabin = 1
\end_layout

\begin_layout Standard

      seqfile='EXAMPLES/enkefa.seq'      
\end_layout

\begin_layout Standard

      varfile='EXAMPLES/enkefa.var'       
\end_layout

\begin_layout Standard

      ntlml = 0              
\end_layout

\begin_layout Standard

      call init_molecule(iabin,grpn,grpc,seqfile,varfile) 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

      seed = 81236       
\end_layout

\begin_layout Standard

      call sgrnd(seed)       
\end_layout

\begin_layout Standard

      upchswitch= 0 
\end_layout

\begin_layout Standard

 
\end_layout

\begin_layout Standard

      nequi=100       
\end_layout

\begin_layout Standard

      nsweeps=100000       
\end_layout

\begin_layout Standard

      nmes=1000       
\end_layout

\begin_layout Standard

      temp = 300             
\end_layout

\begin_layout Standard

      lrand=.true.
        
\end_layout

\begin_layout Standard

      call canon(nequi, nsweeps, nmes, temp,lrand) 
\end_layout

\begin_layout Standard

 
\end_layout

\begin_layout Standard

      end program main
\end_layout

\begin_layout Standard

\begin_inset Caption

\begin_layout Standard
The basic main function for a Monte Carlo Simulation
\begin_inset LatexCommand label
name "listing:mainmc"

\end_inset


\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
The following steps summarize how to run SMMP: 
\end_layout

\begin_layout Enumerate
Assign the path to the directory containing the standard amino acid residue
 libraries and the file 'charges' to the character variable 'libdir' (Line
 10).
\end_layout

\begin_layout Enumerate
Select the force field and solvation model by setting the four paramters
 'flex', 'sh2', 'epsd', and 'itysol' to their appropriate values: 
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

    * ientyp = 0   : ECEPP 
\end_layout

\begin_layout Standard

               1   : FLEX 
\end_layout

\begin_layout Standard

               2   : LUND
\end_layout

\begin_layout Standard

               3   : ECEPP + Abagyan
\end_layout

\begin_layout Standard

   * sh2 =.TRUE.
  : ECEPP/2 potential, sh2=.FALSE.:  ECEPP/3
\end_layout

\begin_layout Standard

   * epsd=.TRUE.
  :  Distant dependent dielectric permittivity
\end_layout

\begin_layout Standard

     epsd=.FALSE.
 : epsilon = 2
\end_layout

\begin_layout Standard

   * itysol = 0   : gas phase,
\end_layout

\begin_layout Standard

     itysol > 0   : approximation of protein-solvent interactions by means
\end_layout

\begin_layout Standard

                    of a solvent accessible surface area approach with
\end_layout

\begin_layout Standard

                    numerical estimation of the accessible area,
\end_layout

\begin_layout Standard

     itysol < 0   : same as above, but the accessible area is calculated
\end_layout

\begin_layout Standard

                    analytically (considerably than itysol > 0).
\end_layout

\begin_layout Standard

   
\backslash
end{verbatim}
\end_layout

\end_inset

 (Line 11--13).
\end_layout

\begin_layout Enumerate

\shape italic
call init_energy(libdir)
\shape default
 to initialize the energy parametrization (Line 12).
\end_layout

\begin_layout Enumerate
Choose the N-terminal and C-terminal groups by assigning to appropriate
 strings to variables 'grpn' and 'grpc' (Line 16--17)
\end_layout

\begin_layout Enumerate
Choose how the initial input is read in: 
\begin_inset ERT
status collapsed

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

   * iabin = 0   : read from PDB-file
\end_layout

\begin_layout Standard

   * iabin = 1   : read from sequence (and configuration) file
\end_layout

\begin_layout Standard

   
\backslash
end{verbatim}
\end_layout

\end_inset

 (Line 18)
\end_layout

\begin_layout Enumerate
Enter the names of the corresponding file(s) '
\shape italic
seqfil
\shape default
' and '
\shape italic
varfil
\shape default
' (Line 19--20).
 If there are empty, they'll be requested through an interactive command
 line dialog, issued by '
\shape italic
call init_molecule
\shape default
' (Line 22).
 The user can easily just supply the corresponding file names in a "here
 document", as shown in the example scripts .
\end_layout

\begin_layout Enumerate
At this point the program is ready for calling task subroutines.
 Here we perform a canonical Monte Carlo simulation at T=300K.
 Two kinds of updates are avaible: a single angle update and the biased
 Gaussian step (bgs).
 For this simulation we turn bgs off by setting 
\family typewriter
upchswitch=0
\family default
.
 Detailed examples for this and other simulation tasks can be found in the
 following section.
 Normally, simulation subroutines write data in output files, but one can
 also use output routines such as `
\shape italic
outpdb
\shape default
' in '
\shape italic
main
\shape default
'.
 The minimal output (written into standard output) is the name of the sequence
 file (extension .seq), name of configuration file (extension .var), and for
 each residue a list of dihedral angles together with their initially assigned
 values.
 
\end_layout

\begin_layout Enumerate
For parallel tempering jobs on on a multiprocessor system one has to replace
 '
\shape italic
main
\shape default
' by '
\shape italic
pmain
\shape default
'.
 The above protocol still applies, but one has to provide in addition the
 number of nodes with the variable '
\shape italic
no
\shape default
'.
 
\end_layout

\begin_layout Section
Programming with SMMP
\end_layout

\begin_layout Standard
While SMMP provides several efficient sampling algorithms, you may want
 to improve an existing or implement a new algorithm.
 This section goes into more details and explains some of the nuts and bolts
 of SMMP.
\end_layout

\begin_layout Paragraph
Where can I find information about atoms, residues, proteins, and dihedrals
\end_layout

\begin_layout Standard
Configurations are stored in one dimensional arrays defined in INCL.H and
 shared through common blocks.
\begin_inset Note Note
status collapsed

\begin_layout Standard
I hope, we'll have moved most of the arrays to modules before publication.
\end_layout

\end_inset

 It helps to think somewhat object oriented to understand the structure
 of the arrays.
 In general integer arrays start with the letter 'i'.
 The abbreviation 'ml' relates to molecules, 'rs' to residues, and 'at'
 to atoms.
 Several boundary arrays are pointers to the first and last element and
 end in '1' for the first element and '2' for the last element.
 For example, irsml1(i) is the index of the first residue in molecule 
\begin_inset Formula $i$
\end_inset

, iatrs1(irsml(i)) is the index of the first atom of the first residue of
 molecule 
\begin_inset Formula $i$
\end_inset

.
 If iat = iatrs1(irsml(i)), then we can access the coordinates of the atom
 using xat(iat), yat(iat), z(iat).
 Using this scheme we can cycle through all the atoms in the system.
 An example is shown in Listing 
\begin_inset ERT
status open

\begin_layout Standard


\backslash
ref{listing:outpdb}
\end_layout

\end_inset

.
 
\begin_inset ERT
status open

\begin_layout Standard


\backslash
lstset{language=Fortran}
\end_layout

\begin_layout Standard


\backslash
begin{lstlisting}[float=p, caption={Using the indices to cycle through all
 the atoms in the system.
 This snippet is taken from the subroutine outpdb, which writes the current
 configuration to a file using the pdb format.}, label=listing:outpdb]
\end_layout

\begin_layout Standard

irs=0
\end_layout

\begin_layout Standard

iat0 = 0
\end_layout

\begin_layout Standard

do inml = nml0, nml1
\end_layout

\begin_layout Standard

   iat = iat0
\end_layout

\begin_layout Standard

   chid = char(64 + inml)
\end_layout

\begin_layout Standard

   ifirs=irsml1(inml)
\end_layout

\begin_layout Standard

   ifiat=iatrs1(ifirs)
\end_layout

\begin_layout Standard

   do nrs=ifirs,irsml2(inml)
\end_layout

\begin_layout Standard

      irs=irs+1
\end_layout

\begin_layout Standard

      res(1:)=seq(nrs)(1:3)
\end_layout

\begin_layout Standard

      do i=iatrs1(nrs),iatrs2(nrs)
\end_layout

\begin_layout Standard

         iat=iat+1
\end_layout

\begin_layout Standard

         atnm=' '
\end_layout

\begin_layout Standard

         atnm(2:5)=nmat(i) ! nmat(i) contains the name of atom i
\end_layout

\begin_layout Standard

         if (atnm(5:5).ne.' ') then
\end_layout

\begin_layout Standard

            atnm(1:1)=atnm(5:5) !!
\end_layout

\begin_layout Standard

            atnm(5:5)=' '
\end_layout

\begin_layout Standard

         endif 
\end_layout

\begin_layout Standard

         z=zat(i)-rz
\end_layout

\begin_layout Standard

         call toupst(atnm) ! converts a string to all uppercase
\end_layout

\begin_layout Standard

         call toupst(res)
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

         write (npdb,1) 'ATOM',iat,atnm,res(1:3),chid,irs,cdin,
\end_layout

\begin_layout Standard

                         xat(i), yat(i),zat(i),occ,bva                 
            
\end_layout

\begin_layout Standard

      enddo 
\end_layout

\begin_layout Standard

   enddo
\end_layout

\begin_layout Standard

enddo
\end_layout

\begin_layout Standard


\backslash
end{lstlisting}
\end_layout

\end_inset


\begin_inset Float table
placement p
wide false
sideways false
status collapsed

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="9" columns="3">
<features>
<column alignment="center" valignment="top" leftline="true" width="0">
<column alignment="center" valignment="top" leftline="true" width="0">
<column alignment="left" valignment="top" leftline="true" rightline="true" width="35col%">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Variable Name 
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Type
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Description
\end_layout

\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
ityat
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
array of int
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Index of type of atom
\end_layout

\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
xat, yat, zat
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
arrays of double
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Cartesian coordinates of atom
\end_layout

\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
cgat
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
array of double
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Partial electric charge on atom
\end_layout

\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
nmat
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
array of character*4
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Name of atom, e.g., C, N, O, H1, H2
\end_layout

\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
iowat
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
array of int
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Index of preceeding atom (see Fig.\InsetSpace ~

\begin_inset LatexCommand ref
reference "fig:Enumeration-of-atoms"

\end_inset

), 0 if no preceeding atom.
\end_layout

\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
iyowat
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
array of int
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Type of bond with preceeding atom.
\begin_inset Note Note
status open

\begin_layout Standard
Maybe, this should be called ityinbdat.
\end_layout

\end_inset


\end_layout

\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
nbdat
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
array of int
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Number of bonds to succeeding atom (outgoing bonds)
\end_layout

\end_inset
</cell>
</row>
<row bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
ibdat
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
two dimensional array of int
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Indices of successor atoms
\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Caption

\begin_layout Standard
\begin_inset LatexCommand label
name "tab:atomic-properties"

\end_inset

List of variables storing atomic properties.
 All the properties of atom 
\begin_inset Formula $i$
\end_inset

 are accessed as the 
\begin_inset Formula $i$
\end_inset

th element of the arrays.
\end_layout

\end_inset


\end_layout

\end_inset


\begin_inset Float table
placement p
wide false
sideways false
status collapsed

\begin_layout Standard
\begin_inset Tabular
<lyxtabular version="3" rows="8" columns="3">
<features>
<column alignment="center" valignment="top" leftline="true" width="0">
<column alignment="center" valignment="top" leftline="true" width="0">
<column alignment="center" valignment="top" leftline="true" rightline="true" width="35col%">
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Name
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Type
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Description
\end_layout

\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
xbaat, ybaat, zbaat
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
3 arrays of double
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Rotation axis for valence angle.
 (see Fig.
 )
\end_layout

\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
baat
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
array of double
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Valence angle in radians
\end_layout

\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
xtoat, ytoat, ztoat
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
3 arrays of double
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Rotation axis for dihedral (torsion) angle.
 (see Fig.)
\end_layout

\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
toat
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
array of double
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Torsion angle defined by iowat(iowat(iowat(i))), iowat(iowat(i)), iowat(i),
 i in radians (see Fig.)
\end_layout

\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
blat
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
array of double
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Length of bond.
\end_layout

\end_inset
</cell>
</row>
<row topline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
ixmsat
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
array of int
\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard
Index of moving set belonging to atom
\end_layout

\end_inset
</cell>
</row>
<row topline="true" bottomline="true">
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
\begin_inset Text

\begin_layout Standard

\end_layout

\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\begin_inset Text

\begin_layout Standard

\end_layout

\end_inset
</cell>
</row>
</lyxtabular>

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Caption

\begin_layout Standard
\begin_inset LatexCommand label
name "tab:dihedral-to-atom"

\end_inset

Each dihedral and valence angle and the corresponding moving set is associated
 with a covalent bond which in turn is defined by its tail atom.
 This table list the related variables.
 
\end_layout

\end_inset


\end_layout

\end_inset


\begin_inset Float figure
wide false
sideways false
status collapsed

\begin_layout Standard
\align center
\begin_inset Graphics
        filename angle_defs.eps
        scaleBeforeRotation
        subcaption

\end_inset


\begin_inset Graphics
        filename dihedral_defs.eps
        scaleBeforeRotation
        subcaption

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Caption

\begin_layout Standard
\begin_inset LatexCommand label
name "fig:angle-defs-in-SMMP"

\end_inset

Angle in SMMP.
 There are two different types of angles in SMMP (and proteins in general):
 bond and torsional angles.
 The bond or valence angle is show in (a).
 The red arrow indicates the rotation axis and is proportional to the cross
 product of the two bonds 
\begin_inset Formula $(1,4)$
\end_inset

 and 
\begin_inset Formula $(4,25)$
\end_inset

making up the angle.
 The angle 
\begin_inset Formula $\alpha$
\end_inset

 is associated with atom 
\begin_inset Formula $4$
\end_inset

.
 The dihedral or torsional angles are rotations around a bond and determined
 by the angles between the two adjacent planes.
 For example, the angle 
\begin_inset Formula $\psi$
\end_inset

 in (b) is the angle between the plane defined by atoms 1, 4, and 25, and
 the plane defined by 4, 25, and 28.
 We could therefore reference this angle using the quadruplet (1, 4, 25,
 28).
 Note that atom 1 is the predecessor of atom 4, atom 4 the predecessor of
 25, and, finally, atom 25 the predecessor of 28.
 SMMP uses this relation to associate the angle 
\begin_inset Formula $\psi$
\end_inset

 with atom 28.
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
Table 
\begin_inset LatexCommand ref
reference "tab:atomic-properties"

\end_inset

 lists the arrays containing the atomic properties such as charge, position,
 and in- and outgoing bonds.
 In the standard geometry configurations can defined by the dihedral angles.
 The variables associated with the angles are given in Table 
\begin_inset LatexCommand ref
reference "tab:dihedral-to-atom"

\end_inset

 and a description of the angles can be found in Fig.\InsetSpace ~

\begin_inset LatexCommand ref
reference "fig:angle-defs-in-SMMP"

\end_inset

.
\end_layout

\begin_layout Paragraph
\begin_inset Note Note
status open

\begin_layout Standard
Why are the names so short and what do they mean?
\end_layout

\begin_layout Paragraph
Setting up a force field
\end_layout

\begin_layout Paragraph
Loading a molecule from a .seq and .var file
\end_layout

\begin_layout Standard
fixed variables, default values, access?
\end_layout

\begin_layout Paragraph
Loading a molecule from a PDB file
\end_layout

\begin_layout Standard
where are things stored? what does regularization do? 
\end_layout

\end_inset


\end_layout

\begin_layout Section
Limitations
\end_layout

\begin_layout Standard
All parameters which limit the usage of SMMP are stored in the file INCL.H.
 The most important ones are listed below.
 The values of these parameters should be changed only in a consistent way!
 
\begin_inset ERT
status collapsed

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

mxml=1              max.
 number of molecules 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

mxrs=100            max.
 total number of residues 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

mxat=2000           max.
 total number of atoms 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

mxbd=3              max.
 number of bonds to following atoms 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

mxvr=mxrs*5         max.
 number of local variables 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

mxms=mxvr*3         max.
 total number of moving sets 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

mxvw=mxat*4         max.
 number of vdw domains
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

mx14=mxat*4         max.
 number of '1-4' partners
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

mxath=100,          max.
 number of atoms in help-arrays 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

mxvrh=mxath         max.
 number of variables in help 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

mxtyat=18           max.
 number of energetic atom-types 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

mxhbdo=4            max.
 types of Hydrogens as donors in HB 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

mxhbac=6            max.
 types of atoms as acceptors in HB 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

mxtyto=19           max.
 number of types of torsional potentials 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

nrsty=35            max.
 number of residue types 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

mxtysol=9           the number of solvation parameters sets 
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset


\end_layout

\begin_layout Standard
\noindent
Note also the following restrictions in the current version of SMMP: 
\end_layout

\begin_layout Enumerate
A single amino acid residue can not be simulated with the FLEX potential
\end_layout

\begin_layout Enumerate
A protein must not start with a prolyl residue.
 
\end_layout

\begin_layout Section
Libraries and Parameter Files
\end_layout

\begin_layout Standard
The residues which can be used with each parameter set are described in
 files 
\shape italic
lib.sh2, lib.sh3
\shape default
, and 
\shape italic
lib.flex
\shape default
, respectively.
 The file 
\shape italic
charges
\shape default
 is needed for N- and C-terminal residues with FLEX parameters.
 The name of the directory, containing these 4 files should be given in
 string 'libdir', which is assigned in module MAIN.
 The choice between parameter sets for potentials ECEPP/2 and ECEPP/3 is
 done by the logical variable '
\shape italic
sh2
\shape default
'.
 The potential FLEX is set by the logical variable '
\shape italic
flex
\shape default
'.
\end_layout

\begin_layout Standard
The amino acid residue libraries contain chemical and structural data for
 each residue according the IUPAC-IUB nomenclature.
 The library files consist of blocks of records with each block representing
 one residue.
 The first line in each block starts with a '#' and contains the name of
 the residue and its total number of atoms.
 Each following line within the block describes one atom.
 Listed are: its name, the bond length and the valence angle to construct
 this atom, the type and the name of corresponding torsion angle, the partial
 charge for the atom, the type of the atom, as well as the previous and
 the following atoms (max.
 3), it is connected to.
 The atom and torsional parameters in the libraries are the same as in the
 original ECEPP/2/3 and FLEX potentials.
 However, it should be noted that SMMP has its own numeration of the atom
 types and the types of torsions (see [1,2] for more details).
\end_layout

\begin_layout Standard
The arrays with the parameters for non bonded pairwise potentials (Van der
 Waals, hydrogen bonds, electrostatic) and the atomic solvation parameters
 are stored in the BLOCK DATA section of '
\shape italic
init_energy.f
\shape default
'.
\end_layout

\begin_layout Standard
SMMP employs 9 different sets of atomic solvation parameters.
 We do not include references to the original works where these sets are
 defined in this document, since this manual is only a supplement to our
 articles 
\begin_inset LatexCommand cite
key "Eisenmenger2001,Eisenmenger2006"

\end_inset

 where all relevant references can be found.
 The set of solvation parameters chosen is indicated by the value of integer
 variable '
\shape italic
itysol
\shape default
' in the MAIN module.
 If setting 
\shape italic
itysol
\shape default
 to a positive value between 
\shape italic
1
\shape default
 and 
\shape italic
9
\shape default
 in MAIN, the numerical method 
\shape italic
enysol
\shape default
 is applied to compute the solvation energy term.
 By choosing a negative integer value for 
\shape italic
itysol
\shape default
 from the interval 
\shape italic
[-1,-9]
\shape default
, the analytical method 
\shape italic
esolan
\shape default
 is used to calculate the solvation energy.
 The tesselation points for numerically calculating the solvent accessible
 surface area have to be provided in an external file (named 
\shape italic
tes.dat
\shape default
 in our package) and read in during initialization of solvation parameters
 in 
\shape italic
init_energy.f
\shape default
.
\end_layout

\begin_layout Section
Input Files
\end_layout

\begin_layout Standard
SMMP requires an input file that specifies the sequence of amino acid residues
 of the protein in plain ASCII-format.
 
\end_layout

\begin_layout Subsection
PDB-File
\begin_inset LatexCommand label
name "sub:PDB-File"

\end_inset


\end_layout

\begin_layout Standard
Setting the variable '
\shape italic
iabin = 0
\shape default
' in 
\shape italic
main.f
\shape default
 the sequence of amino acids is read from a PDB-file - the standard format
 in which protein structures are deposited in the Protein Data Bank.
 The atomic coordinates are also read from the PDB-file and can serve as
 a start configuration.
 However, the fixed bond lengths and angles in the standard geometry will
 slightly differ from the actual bond lengths and angles in the PDB-structure.
 Forcing the molecule into standard bonding geometry corresponding to a
 given potential may lead to un-physically high energies.
 Regularization through 
\shape italic
regul.f
\shape default
 allows to obtain an optimized structure with standard bonding geometry
 with low internal energy without differing significantly from the PDB structure.
 
\end_layout

\begin_layout Subsection
Sequence File
\begin_inset LatexCommand label
name "sub:Sequence-File"

\end_inset


\end_layout

\begin_layout Standard
Setting `
\shape italic
iabin = 1
\shape default
' the amino acid sequence is read from a separate sequence file.
 Its first line must start with a '#' and may contain the name for the molecule.
 The residues in the following lines should be named as in the library files
 
\shape italic
lib.sh2, lib.sh3
\shape default
, or 
\shape italic
lib.flex
\shape default
.
 Residue names are not case-sensitive and should be separated from each
 other by at least one white space.
\end_layout

\begin_layout Standard
Currently, the following residue types can be used in SMMP: 
\end_layout

\begin_layout Enumerate
Neutral:
\newline
 ala, arg, asn, asp, cys, gln, glu, gly, his* ; hise* ; hyp*, ile,
 leu, lys, met, phe, pro* , ser, thr, trp, tyr, val
\newline
 (where the residues
 marked by an asterix are characterized by:
\newline
 his - hydrogen at N-delta atom
\newline

 hise - hydrogen at N-epsilon atom
\newline
 pro, hyp - down-puckering) 
\end_layout

\begin_layout Enumerate
Charged:
\newline
 arg+, asp-, glu-, his+, lys+.
 
\end_layout

\begin_layout Enumerate
Variants, only with ECEPP/3 parameters:
\newline
 hypu, prou - up-puckering
\newline
 cpro,
 cpru - cis-Pro with down-, up-puckering
\newline
 pron, pro+ - N-terminal neutral,
 charged with respect to NH2+ Pro 
\end_layout

\begin_layout Standard
End-groups need to be specified in 
\shape italic
main.f
\shape default
 and are added through subroutine 
\shape italic
addend
\shape default
 to the N- and C-terminus, correspondingly.
 Possible values for the end groups are nh2 and nh3+ for the N terminal
 and cooh and coo- for the C terminal.
 Note, that the acetyl group ('
\shape italic
ace
\shape default
') and N'methylamide ('
\shape italic
nme
\shape default
') need to be added as 
\shape italic
residues
\shape default
 in the sequence file.
 In that case, input into '
\shape italic
addend
\shape default
' will be ignored by SMMP.
 Note also, that at present, molecules with only one single residue cannot
 be simulated with the FLEX data set and the first residue should not be
 a prolyl residue.
\end_layout

\begin_layout Standard
An example sequence file (provided with SMMP) may look as follows: 
\begin_inset ERT
status collapsed

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

------------------- enkefa.seq -------------------------- 
\end_layout

\begin_layout Standard

# Met-Enkephalin 
\end_layout

\begin_layout Standard

Tyr Gly Gly Phe Met 
\end_layout

\begin_layout Standard

--------------------------------------------------------- 
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset


\end_layout

\begin_layout Subsection
Configuration File (Dihedrals)
\begin_inset LatexCommand label
name "sub:Configuration-File-(Dihedrals)"

\end_inset


\end_layout

\begin_layout Standard
With option '
\shape italic
iabin = 1
\shape default
' SMMP allows to provide a designated start configuration by listing dihedral
 angles in a second input file.
 If no name of any configuration file is given (or the name of a non-existing
 file is entered), all variables retain their default values as defined
 in the libraries.
\end_layout

\begin_layout Standard
This configuration file has to follow a fixed structure in which each line
 can be considered as a COMMAND for subroutine '
\shape italic
redvar
\shape default
'.
 The following syntax has to be used in each COMMAND: RESIDUE : VARIABLE
 : VALUE Hence, each line can consist of up to 3 FIELDS, separated by an
 ':'.
 In the first field the RESIDUE is selected through an INTEGER number which
 marks its position in the amino acid sequence.
 The second field should contain a string with the name of the VARIABLE,
 i.e.
 names the specific dihedral angle.
 The last field provides the value for the VARIABLE (a REAL number) and
 is mandatory.
 A symbol '&' following this number indicates that the variable will be
 fixed to that value throughout the whole simulation process.
 Spaces are not significant and are therefore ignored.
 Empty COMMANDS, as ' : : ', and empty lines or lines containing '#' are
 ignored.
 Missing fields are interpreted as 'for all': 
\begin_inset ERT
status collapsed

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

1 : phi : 180         Set phi of residue #1 to 180 degrees 
\end_layout

\begin_layout Standard

1 : phi : 180&        Keep phi of residue #1 fixed to 180 degrees 
\end_layout

\begin_layout Standard

phi : 180             Set phi  of ALL residues to 180 degrees 
\end_layout

\begin_layout Standard

180                   Set all variables to 180 degrees 
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

 Several consecutive residues or variables can be indicated by ZONES of
 indices.
 Several NAMES can be indicated by wild-card ('*') and are case-sensitive:
 
\begin_inset ERT
status collapsed

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

1-4 : phi : 180       Set 'phi' of residues #1,#2,#3, and #4 to 180 deg.
 
\end_layout

\begin_layout Standard

5 : x* : 60           Set all xi-angles of residue #5 to 60 deg.
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

 Several NAMES or INDICES may be given in the same field, when separated
 by ','.
 Similarly, several commands may be given on the same line and must be separated
 by ';' 
\begin_inset ERT
status collapsed

\begin_layout Standard


\backslash
begin{verbatim} 
\end_layout

\begin_layout Standard

phi, psi : -30        Set all phi & psi to -30 deg.
 
\end_layout

\begin_layout Standard

phi:-65; psi:-45      Set all phi=-65, all psi=-45 
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

 Note, that dihedral angles are defined slightly differently in SMMP than
 in standard ECEPP (residue index in parenthesis): 
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

 - psi of the i-th residue = defined by N (i-1) - CA(i-1) - C (i-1) - N(i)
 
\end_layout

\begin_layout Standard

 - omg of the i-th residue = defined by CA(i-1) - C (i-1) - N (i) - CA(i)
 
\end_layout

\begin_layout Standard

 - phi for the i-th residue = defined by C (i-1) - N (i) - CA(i) - C(i)
 
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

 except: 
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

phi for the 1st residue = defined by H1(1) - N (1) - CA(1) - C(1) 
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

 (H2-atom in the N-terminal NH2-group is added via dihedral 'H2-N-CA-C'=
 phi + 120) 
\end_layout

\begin_layout Standard
If a molecule consists of n residues then: 
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

 - pst = defines dihedral N (n) - CA(n) - C (n) - Oxt(n) 
\end_layout

\begin_layout Standard

 - omt = defines dihedral CA(n) - C (n) - Oxt(n) - Hxt(n) 
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

 (Oxt & Hxt comprise the hydroxyl of the C-terminal carboxyl group)
\end_layout

\begin_layout Standard
The following example configuration file 
\shape italic
enkefa.var
\shape default
 is provided with the program and may be used with the sequence file 
\shape italic
enkefa.seq
\shape default
: 
\begin_inset ERT
status collapsed

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

------------------- enkefa.var -------------------------- 
\end_layout

\begin_layout Standard

1 : phi :  -86.24 
\end_layout

\begin_layout Standard

1 : x1  : -172.59 
\end_layout

\begin_layout Standard

1 : x2  :   78.71 
\end_layout

\begin_layout Standard

1 : x6  : -165.88 
\end_layout

\begin_layout Standard

2 : psi :  156.18 
\end_layout

\begin_layout Standard

2 : omg :  180.00 
\end_layout

\begin_layout Standard

2 : phi : -154.53 
\end_layout

\begin_layout Standard

3 : psi :   83.64 
\end_layout

\begin_layout Standard

3 : omg :  180.00 
\end_layout

\begin_layout Standard

3 : phi :   83.66 
\end_layout

\begin_layout Standard

4 : psi :  -73.86 
\end_layout

\begin_layout Standard

4 : omg :  180.00 
\end_layout

\begin_layout Standard

4 : phi : -137.04 
\end_layout

\begin_layout Standard

4 : x1 :    58.79 
\end_layout

\begin_layout Standard

4 : x2 :    94.60 
\end_layout

\begin_layout Standard

5 : psi :   19.33 
\end_layout

\begin_layout Standard

5 : omg : -180.00 
\end_layout

\begin_layout Standard

5 : phi : -163.63 
\end_layout

\begin_layout Standard

5 : x1 :    52.76 
\end_layout

\begin_layout Standard

5 : x2 :   175.28 
\end_layout

\begin_layout Standard

5 : x3 :  -179.83 
\end_layout

\begin_layout Standard

5 : x4 :   -58.57 
\end_layout

\begin_layout Standard

5 : pst :  160.45 
\end_layout

\begin_layout Standard

5 : omt :  180.00 
\end_layout

\begin_layout Standard

--------------------------------------------------------- 
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Standard
\align center
\begin_inset Graphics
        filename atom_numbering.eps
        scaleBeforeRotation

\end_inset


\end_layout

\begin_layout Standard
\begin_inset Caption

\begin_layout Standard
\begin_inset LatexCommand label
name "fig:Enumeration-of-atoms"

\end_inset

Enumeration of atoms in SMMP.
 Atoms are numbered starting from the N terminal of the protein.
 The terminal nitrogen has the index 1.
 Counting continues with the two attached hydrogens and then moves along
 the backbone.
 After the C
\begin_inset Formula $_{\alpha}$
\end_inset

, we count along the side chain following a breadth-first scheme.
 Rings are enumerated counter clockwise.
 
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Section
Frequently used Functions and Subroutines
\begin_inset LatexCommand label
name "sec:Frequently-used-Functions"

\end_inset


\end_layout

\begin_layout Subsection
Task Subroutines
\end_layout

\begin_layout Standard
In the following we describe some important simulation subroutines and their
 requisites.
 For more information see [1,2].
 Following the philosophy behind SMMP these routines are rather simple and
 may serve as templates which the user can modify according to his special
 needs.
 
\end_layout

\begin_layout Subsubsection
Subroutine init_molecule(iabin, grpn, grpc, seqfile, varfile)
\end_layout

\begin_layout Standard
(Usage: '
\emph on
call init_molecule(iabin, grpn, grpc, seqfile, varfile)')
\end_layout

\begin_layout Standard
Initializes a new molecule and adds it to the system.
 The information is either read from a sequence (see 
\begin_inset LatexCommand ref
reference "sub:Sequence-File"

\end_inset

) and, optionally, a variable file (see 
\begin_inset LatexCommand ref
reference "sub:Configuration-File-(Dihedrals)"

\end_inset

) if 
\emph on
iabin=1
\emph default
 or from a pdb file (see 
\begin_inset LatexCommand ref
reference "sub:PDB-File"

\end_inset

) if 
\emph on

\begin_inset Formula $iabin\neq1$
\end_inset


\emph default
.
 If the molecule is read from a pdb file, the name of the file is given
 in 
\emph on
seqfile
\emph default
.
 By repeatedly calling init_molecule, you can add several interacting molecules.
 The N-terminal group is determined by 
\emph on
grpng
\emph default
 and the C-terminal group 
\emph on
grpc.
\end_layout

\begin_layout Subsubsection
Subroutine REGUL(nml, iter, nsteps, 
\begin_inset Formula $\varepsilon$
\end_inset

)
\begin_inset LatexCommand index
name "REGUL"

\end_inset

 (file regul.f)
\end_layout

\begin_layout Standard
(Usage: '
\shape italic
call regul(nml, iter, nsteps, 
\begin_inset Formula $\varepsilon$
\end_inset

)
\shape default
')
\end_layout

\begin_layout Standard
For a given PDB-structure the actual bond lengths and bond angles generally
 differ from those in the standard geometry model assumed with the ECEPP
 or FLEX potential.
 This subroutine is applied to determine the configuration within the standard
 geometry that is as close as possible to a given PDB-structure with an
 energy as low as possible.
 This process of fitting a PDB structure into standard geometry is called
 regularization.
 '
\shape italic
regul
\shape default
' requires the PDB-structure to be read into SMMP by setting '
\shape italic
iabin = 0
\shape default
' in '
\shape italic
main
\shape default
'.
 With this option, `
\shape italic
init_molecule
\shape default
' calls the subroutines `
\shape italic
pdbread
\shape default
' and `
\shape italic
pdbvars
\shape default
' that also to measure the dihedral angles in the PDB-structure.
 Using these dihedral angles a first model of the molecule is built using
 standard bonding geometry.
 Hence, '
\shape italic
regul
\shape default
' has to be called AFTER '
\shape italic
init_molecule
\shape default
'.
 '
\shape italic
nml
\shape default
' has to be set to 1 in the present version of SMMP.
\end_layout

\begin_layout Standard
'
\shape italic
regul
\shape default
' starts with a minimization of the initial structure using only the sum
 of squared distances between atom positions of the SMMP structure to the
 PDB-structure as 
\begin_inset Quotes erd
\end_inset

constraint energy
\begin_inset Quotes erd
\end_inset

.
 After this initial step, a list of bad atom contacts, i.e.
 atoms with vdW-energy of more than 2 kcal/mol (as calculated by '
\shape italic
cnteny
\shape default
') and the root-mean-square-deviation (rmsd) to the PDB-structure is printed
 out.
 In a second step, the physical energy is minimized, allowing only hydrogens
 to move, and bad contacts and the rmsd are evaluated, again.
 A number of iterations follow where a composite energy as the weighted
 sum of physical and constraint energy is minimized.
 In this iterations the weight of the constraint energy is successively
 lowered to zero, and that of the physical energy raised to one.
 At the end, the dihedral angles of the final structure are printed out
 together with its rmsd and list of remaining bad contacts.
 
\end_layout

\begin_layout Subsubsection
Subroutine MINIM(imin, maxit, 
\begin_inset Formula $\varepsilon$
\end_inset

)
\begin_inset LatexCommand index
name "MINIM"

\end_inset

 (file minim.f):
\end_layout

\begin_layout Standard
(Usage: 
\shape italic
'call minim(imin
\shape default
, maxit, 
\begin_inset Formula $\varepsilon$
\end_inset

)')
\newline
 This subroutine minimizes the current configuration of the molecule.
 It can be called from any point during the simulation once a configuration
 is defined.
 When calling this subroutine one needs to specify the type of minimizer
 through variable '
\shape italic
imin
\shape default
'.
 Setting '
\shape italic
imin = 1
\shape default
' chooses a Quasi-Newton minimizer by calling '
\shape italic
minqsn
\shape default
', '
\shape italic
imin = 2
\shape default
' a Conjugate Gradient minimizer ('
\shape italic
mincjg
\shape default
').
 The performance of these minimizers can be controlled by setting various
 parameters in MINIM.
 The two most commonly used ones, the accuracy ('
\begin_inset Formula $\varepsilon$
\end_inset

') and the total number of function calls 'mxit' are passed as arguments.
\end_layout

\begin_layout Subsubsection
Subroutine CANON(nequi, nswp, nmes, temp, lrand)
\begin_inset LatexCommand index
name "CANON"

\end_inset

 (file canon.f):
\end_layout

\begin_layout Standard
(Usage: '
\emph on
call canon(nequi, nswp, nmes, temp, lrand)
\emph default
')
\newline
The subroutine carries out a canonical simulation at temperature 'temp'.
 The simulation starts from a random configuration if the logical parameter
 'lrand' is set to 
\shape italic
.TRUE.
\shape default
.
 Otherwise the simulation starts from the current conformation of dihedral
 angles as stored in array 'vlvr'.
 One also has to set the number of Monte Carlo sweeps for the simulation
 'nswp', and the equilibration 'nequi', as well as the number 'nmes' of
 Monte Carlo sweeps between measurements.
 Three output files are created: files `start.pdb' and 'final.pdb' are for
 storing the start and final configurations of the molecule, respectively,
 in a data format compatible with Protein Data Bank.
 The file 'time.d' contains the time series of some quantities.
 In our template we measure and store in this file the total energy 'eol';
 the radius-of-gyration `rgy' (by means of subroutine RGYR (
\begin_inset LatexCommand ref
reference "ite:Subroutine-RGYR"

\end_inset

)); the number of helical (
\begin_inset Formula $\beta$
\end_inset

-sheet-like) residues 'nhel' ('nbet') and segments 'mhel' (`mbet') using
 subroutine HELIX (
\begin_inset LatexCommand ref
reference "ite:subroutine-HELIX"

\end_inset

); and the number of hydrogen bonds 'mhb' calculated through subroutine
 HBOND (
\begin_inset LatexCommand ref
reference "ite:Subroutine-HBOND"

\end_inset

).
 
\end_layout

\begin_layout Subsubsection
Subroutine ANNEAL(nequi, nswp, nmes, tmax, tmin, lrand)
\begin_inset LatexCommand index
name "ANNEAL"

\end_inset

 (file: anneal.f):
\end_layout

\begin_layout Standard
(Usage: '
\emph on
call anneal(nequi, nswp, nmes, tmax, tmin, lrand)
\emph default
')
\end_layout

\begin_layout Standard
This subroutine allows for optimization of protein conformations by means
 of simulated annealing.
 When the logical parameter 'lrand' is set to 
\shape italic
.TRUE.

\shape default
 then the program will start from a random configuration.
 Otherwise, the annealing process will start from the current configuration
 as stored in the array 'vlvr'.
 You have to set the initial and final temperatures 'tmax' and 'tmin', the
 number of Monte Carlo sweeps for simulation nswp and equilibration 'nequi',
 and the number 'nmes' of Monte Carlo sweeps between measurements.
 Four output files are created in the same directory where the executable
 is running: three of them contain the start (start.pdb), the final (final.pdb)
 and the global minimum configuration (global.pdb), respectively, the 4th
 file (time.d) contains the time series of the simulation.
 In the presented template we measure and store in this file the actual
 temperature 'temp', the total energy 'eol', the radius-of-gyration 'rgy'
 (as calculated by subroutine RGYR) and the Zimmerman code (as character
 variable 'zimm') of the present configuration as obtained through subroutine
 ZIMMER.
 
\end_layout

\begin_layout Subsubsection
Subroutine MULCAN_PAR(nsweep, nup, temp, kmin, kmax, binWidth, l_iter)
\begin_inset LatexCommand index
name "MULCANPAR"

\end_inset

 (file mulcan_mod_par.f):
\end_layout

\begin_layout Standard
This subroutine is part of the module 
\emph on
multicanonical
\emph default
.
 To use the function include the module with 
\emph on
use multicanonical
\emph default
 in your main file.
 The subroutine calculates multicanonical weight factors and has two working
 modes.
 One is for improving the already existing set of multicanonical parameters
 through further iterations, and another to calculate them anew.
 In the first case the logical variable 'l_iter' is set to the value 
\shape italic
.TRUE.
\shape default
.
 The histogram from a preliminary simulation as well as the existing values
 of the parameters are read from the file 'mpar_full.d'.
 In the second case ( 'l_iter' = .FALSE.) all arrays are initialized to zero.
 The values of 'kmin' and 'kmax' together with and the size of the energy
 bin 'ebinWidth' determine the energy range .
 The total number of Monte Carlo sweeps is given by 'nsweep', 'nup' is the
 number of Monte Carlo sweeps between updates of the multicanonical parameters,
 and 'temp' is the temperature of the initial canonical simulation.
 Every 'nup' sweeps the histogram of the preliminary simulation as well
 as the existing values of the parameters are written to the file 'mpar_full.d'.
 The final multicanonical parameters are written into the file 'muca.d'.
 
\end_layout

\begin_layout Subsubsection
Subroutine MULCAN_SIM(nequi, nsweeps, nmes, nsave, kmin, kmax, binWidth,
 restart)
\begin_inset LatexCommand index
name "MULCANSIM"

\end_inset

 (file mulcan_sim.f):
\end_layout

\begin_layout Standard
This subroutine performs a Monte Carlo simulation of a protein using multicanoni
cal weights.
 Information necessary for a re-start are saved after every 'nsave' Monte
 Carlo moves into the file 'start.d'.
 You can restart a simulation by setting 'restart'=.TRUE.
 otherwise the simulation starts from a random configuration.
 Parameters 'binWidth', 'kmin', and 'kmax' set the energy-bin size and the
 lower and upper limits of the energy interval, within which the multicanonical
 parameters were defined (see MULCAN_PAR).
 These parameters are read from the file 'muca.d' and have to be the same
 as the ones used in MULCAN_PAR to generate the multicanonical weights.
 The total number of Monte Carlo sweeps is 'nsweep', the number of Monte
 Carlo sweeps needed for equilibration is 'nequi', and the interval between
 successive measurements is 'nmes'.
 In our example the output goes to 'time.d', in which the time series of
 the simulation is written.
 Measured quantities are the total potential energy 'eol', the number of
 contacts 'nhx' and the number of native contacts 'nhy'.
 The latter number counts the contacts that are the same in the present
 configuration and the target structure.
 Also measured is the Hamming distance 'dham' between the present and the
 target configuration.
 The latter three quantities are calculated by the subroutine CONTACTS.
 The contact map needs to be initialized before calling mulcan_sim., for
 example with the following code:
\begin_inset ERT
status collapsed

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

open(9,file='enkefa.ref')
\end_layout

\begin_layout Standard

nresi=irsml2(1)-irsml1(1) + 1 
\end_layout

\begin_layout Standard

! nresi: Number of residues 
\end_layout

\begin_layout Standard

! Read reference contact map 
\end_layout

\begin_layout Standard

nci = 0 
\end_layout

\begin_layout Standard

do i=1,nresi 
\end_layout

\begin_layout Standard

   read(9,*) (iref(i,j) , j=1,nresi) 
\end_layout

\begin_layout Standard

end do
\end_layout

\begin_layout Standard

do i=1,nresi 
\end_layout

\begin_layout Standard

   do j=nresi,i+3,-1 
\end_layout

\begin_layout Standard

      if(iref(i,j).eq.1) nci = nci + 1 
\end_layout

\begin_layout Standard

   end do 
\end_layout

\begin_layout Standard

end do 
\end_layout

\begin_layout Standard

write(*,*) 'Number of contacts in reference conformation:',nci 
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset


\end_layout

\begin_layout Subsubsection
Subroutine PARTEM_S
\begin_inset LatexCommand index
name "PARTEMS"

\end_inset

 
\end_layout

\begin_layout Standard
(file partem_s.f):
\end_layout

\begin_layout Standard
This parameterless subroutine is designed to simulate a protein by means
 of the parallel tempering technique on a single processor.
 Before running a parallel tempering simulation using PARTEM_S one has to
 set the following variables in this subroutine: the number of replicas
 ('no') and the initial temperatures on each replica (array 'temp(no)');
 the sum of the number of degrees of freedom over all replicas ('nvrmax');
 the number of Monte Carlo sweeps at equilibration ('nequi') and the number
 of Monte Carlo sweeps between measurements ('nmes').
 Except for re-starts, the logical variable 'lstart' should be set to .FALSE.,
 in which case all dihedral angles are set to random values.
 At the end of the simulation all dihedral angles are stored in the file
 'startconf.d', from which the program reads its start configuration, if
 'lstart=.TRUE.'.
 In the simulation, measurements are made every 'nmes' Monte Carlo sweeps.
 In our template, we measure for each replica the radius-of gyration 'rgy'
 and the end-to-end distance 'ee' by means of subroutine RGYR and write
 both values together with the temperature 'temp0' , total energy 'energy',
 Monte Carlo time 'nsw', and the index of the replicas 'k1' to an output
 file 'time.d'.
 
\end_layout

\begin_layout Subsubsection
PMAIN and subroutine PARTEM_P
\begin_inset LatexCommand index
name "PARTEMP"

\end_inset

 (files pmain.f and partem_p.f)
\end_layout

\begin_layout Standard
(Usage: '
\emph on
call partem_p(no, nequi, nswp, nmes, newsta, switch)
\emph default
')
\end_layout

\begin_layout Standard
PMAIN and PARTEM_P are used for parallel tempering simulations on a parallel
 computer with 'no' nodes.
 PMAIN replaces MAIN in this case.
 Both PMAIN and PARTEM_P utilize the MPI message-passing routines.
 The number of nodes 'no' has to be set in the main program and equals the
 number of replicas in the parallel tempering method.
 In addition, one has to pass the following variables to PARTEM_P: the number
 of Monte Carlo sweeps for equilibration nequi and the total simulation
 nswp; and the number of Monte Carlo sweeps between measurements ('nmes').
 Except for restarts the logical variable 'newsta' should be set to .FALSE..
 If newsta is .TRUE., switch determines the starting configuration.
 If switch=1, all dihedral angles are set to the random values.
 If switch=-1, all dihedral angles are set to 180.
 If switch=0, the configuration remains unchanged.
 At the end of the simulation all dihedral angles are stored in the file
 'par_R.in', from which the program reads its start configurations if 'newsta=.TRU
E.'.
 Before running the program one has to prepare the file 'temp.d' with 'no'
 lines.
 Each line lists the index of replica 'j' and its temperature 'temp'.
 In our template we measure every 'nmes' Monte Carlo sweeps for each replica
 a number of quantities: the radius of gyration 'rgy', the number of residues
 'nhel' and segments 'mhel' in an 
\begin_inset Formula $\alpha$
\end_inset

-helix, the number of residues in a 
\begin_inset Formula $\beta$
\end_inset

-sheet 'nbet' and the number of such segments 'mbet', the number of hydrogen
 bonds 'mhb', and the number of contacts 'nctot' and native contacts 'ncnat'.
 The latter number counts the contacts which are same in the present configurati
on and in the target structure For this, one has to prepare in advance the
 file 'reference.d' with the contact matrix of the target structure.
 All measured quantities are written together with energy, temperature and
 the index of the corresponding replica in the file 'ts.d'.
 At the end of the simulation the average energy and specific heat for each
 temperature/replica and the acceptance rate of replica-exchange moves are
 written to standard output.
 
\end_layout

\begin_layout Subsection
Useful Subroutines
\end_layout

\begin_layout Subsubsection
Subroutine CONTACTS
\begin_inset LatexCommand index
name "CONTACTS"

\end_inset


\end_layout

\begin_layout Standard
(Usage: 
\shape italic
call contacts(ncn,nham2,dham)
\shape default
):
\end_layout

\begin_layout Standard
This subroutine calculates the matrix of the van-der-Waals contacts between
 C
\begin_inset Formula $^{\alpha}$
\end_inset

-atoms for a given configuration.
 'ncn' is the total number of such contacts, 'nham2' the number of native
 contacts (i.e.
 such con- tacts which are the same in the present configuration and the
 reference configuration), and the Hamming distance 'dham' between the present
 and the target configuration.
 
\end_layout

\begin_layout Subsubsection
Subroutine CNTENY
\begin_inset LatexCommand index
name "CNTENY"

\end_inset

:
\end_layout

\begin_layout Standard
(Usage: 
\emph on
call cnteny(nml)
\emph default
)
\end_layout

\begin_layout Standard
The subroutine '
\emph on
cnteny
\emph default
' displays a list of heavy atoms in molecule '
\emph on
nml
\emph default
' that have a contact energy of more than 2 kcal/mol.
 If one sets the parameter '
\emph on
ieyel = 0
\emph default
' in '
\emph on
cnteny
\emph default
' the the contact energy is calculated with the van-der-Waals energy term,
 only.
 Setting '
\emph on
ieyel = 1
\emph default
' additionally includes the electrostatic energy into the contact energy,
 and bad contacts are displayed if this energy exceeds a value of 10 kcal/mol
 for an atom.
 
\end_layout

\begin_layout Subsubsection
Functions ENERGY
\begin_inset LatexCommand index
name "ENERGY"

\end_inset

, ENYSHE
\begin_inset LatexCommand index
name "ENYSHE"

\end_inset

, ENYFLX
\begin_inset LatexCommand index
name "ENYFLX"

\end_inset

, ENYSOL
\begin_inset LatexCommand index
name "ENYSOL"

\end_inset

, ESOLAN
\begin_inset LatexCommand index
name "ESOLAN"

\end_inset

, and ENYREG
\begin_inset LatexCommand index
name "ENYREG"

\end_inset

:
\end_layout

\begin_layout Standard
(Usage: 
\shape italic
eny = energy()
\shape default
)
\newline
 The real*8 function `
\shape italic
energy
\shape default
' is a wrapping function that calculates the energy of a given configuration.
 Depending on the choice of parameters '
\shape italic
flex
\shape default
', '
\shape italic
sh2
\shape default
', '
\shape italic
itysol
\shape default
' and '
\shape italic
ireg
\shape default
' in '
\shape italic
main
\shape default
' ('
\shape italic
pmain
\shape default
') the `vacuum' energy of the protein is calculated by the functions '
\shape italic
enyshe
\shape default
' (ECEPP/2 or ECEPP/3), or '
\shape italic
enyflex
\shape default
' (FLEX), and the solvation energy using the solvent accessible area method
 with '
\shape italic
enysol
\shape default
' (approximate, but fast estimation of the solvated area) or '
\shape italic
esolan
\shape default
' (analytical, but slower calculation of the area).
 '
\shape italic
enyreg
\shape default
' calculates the constraint energy term needed during regularization of
 PDB-structures.
 '
\shape italic
energy
\shape default
' returns the sum of these energy terms as selected by the parameters in
 the 'main'-module.
 
\end_layout

\begin_layout Subsubsection
Subroutine GRADIENT
\begin_inset LatexCommand index
name "GRADIENT"

\end_inset

, OPESHE
\begin_inset LatexCommand index
name "OPESHE"

\end_inset

, OPEFLX
\begin_inset LatexCommand index
name "OPEFLX"

\end_inset

, OPESOL
\begin_inset LatexCommand index
name "OPESOL"

\end_inset

, and OPEREG
\begin_inset LatexCommand index
name "OPEREG"

\end_inset

:
\end_layout

\begin_layout Standard
(Usage: 
\shape italic
call gradient()
\shape default
)
\newline
 The wrapping subroutine '
\shape italic
gradient
\shape default
' calculates the energy and partial derivatives (with respect to internal
 degrees of freedom) for a given protein configuration.
 Depending on the choice of parameters '
\shape italic
flex
\shape default
', '
\shape italic
sh2
\shape default
', '
\shape italic
itysol
\shape default
', and '
\shape italic
ireg
\shape default
', the subroutines '
\shape italic
opeshe
\shape default
' (ECEPP/2 or ECEPP/3), '
\shape italic
opeflx
\shape default
' (FLEX), '
\shape italic
opesol
\shape default
' (solvent accessible surface area) and/or '
\shape italic
opereg
\shape default
' (constraint energy term during regularization of PDB structures) are selected
 and contribute to the total energy and its gradient that is calculated.
 
\end_layout

\begin_layout Subsubsection
\begin_inset LatexCommand label
name "ite:Subroutine-HBOND"

\end_inset

Subroutine HBOND
\begin_inset LatexCommand index
name "HBOND"

\end_inset


\end_layout

\begin_layout Standard
(Usage: 
\shape italic
call hbond(nml,mhb,ipr)
\shape default
):
\newline
 This subroutine determines the number 'mhb' of the hydrogen bonds for
 the current conformation of the molecule and requires 'nml' as input -
 the index of the present molecule.
 The hydrogen bonds are printed out for '
\begin_inset Formula $ipr>0$
\end_inset

'.
 
\end_layout

\begin_layout Subsubsection
\begin_inset LatexCommand label
name "ite:subroutine-HELIX"

\end_inset

subroutine HELIX
\begin_inset LatexCommand index
name "HELIX"

\end_inset


\end_layout

\begin_layout Standard
(Usage: 
\shape italic
helix(nhel,mhel,nbet,mbet)
\shape default
): 
\newline
 HELIX determines whether a residue is part of an 
\begin_inset Formula $\alpha$
\end_inset

-helix or 
\begin_inset Formula $\beta$
\end_inset

-sheet according to its backbone dihedral angles (
\begin_inset Formula $\phi,\psi$
\end_inset

) (ranges defined in a PARAMETER statement) and returnes the number of helical
 residues 'nhel', the number of helical segments 'mhel', and the corresponding
 quantities for 
\begin_inset Formula $\beta$
\end_inset

-strand elements 'nbet' and 'mbet'.
 
\end_layout

\begin_layout Subsubsection
\begin_inset LatexCommand label
name "ite:Subroutine-METROPOLIS"

\end_inset

Subroutine METROPOLIS
\begin_inset LatexCommand index
name "METROPOLIS"

\end_inset


\end_layout

\begin_layout Standard
(Usage: 
\shape italic
call metropolis(eol,acz,weight)
\shape default
): 
\newline
 The subroutine implements one Metropolis move for every dihedral angle
 and requires as input a weight function '
\shape italic
weight(eol)
\shape default
' and the energy 'eol' of the present configuration.
 It returns in the variable 'eol' the energy of the configuration after
 'nvr' (the number of non-fixed dihedral angles) updates.
 'acz' accounts for the number of Metropolis moves were the proposed configurati
on was accepted.
 
\end_layout

\begin_layout Subsubsection
Subroutine OUTPDB
\begin_inset LatexCommand index
name "OUTPDB"

\end_inset


\end_layout

\begin_layout Standard
(Usage: 
\shape italic
call outpdb(nml,pdbFileName)
\shape default
):
\newline
 The subroutine writes in the output file the coordinates of the atoms
 of given molecule.
 The format is compatible with the standard data representation format of
 the Brookhaven Protein Data bank.
 This subroutine requires as input the index 'nml' of the given molecule
 and the file name of the output-file.
 If nml=0, the configuration for all molecules in the system is written
 to a multi-model pdb file.
\end_layout

\begin_layout Subsubsection
Subroutine OUTVAR
\begin_inset LatexCommand index
name "OUTVAR"

\end_inset


\end_layout

\begin_layout Standard
(Usage: 
\shape italic
call outvar(nml, filename)
\shape default
):
\end_layout

\begin_layout Standard
This subroutine writes the dihedral angles of the current configuration
 of molecule '
\shape italic
nml
\shape default
' to either standard output ('filename = 
\begin_inset Quotes eld
\end_inset

 
\begin_inset Quotes eld
\end_inset

') or a dedicated file, where filename is the name of the file).
 The dihedral angles are written out in a form that allows to use them as
 configuration input file for SMMP.
 If nml=0, the configuration for all molecules in the system is printed.
 
\end_layout

\begin_layout Subsubsection
Function grnd() and subroutine sgrnd(seed):
\end_layout

\begin_layout Standard
Our package includes an implementation of the twister-mersenne random generator.
 Initialize the random number generator using 
\emph on
call sgrnd(seed)
\emph default
, where 
\emph on
seed
\emph default
 is an integer.
 Each call off 
\emph on
grnd()
\emph default
 returns a new random number between 0 and 1 taken from a uniform distribution.
\end_layout

\begin_layout Subsubsection
\begin_inset LatexCommand label
name "ite:Subroutine-RGYR"

\end_inset

Subroutine RGYR
\end_layout

\begin_layout Standard
(Usage: 
\shape italic
call rgyr(nml,rgy,ee)
\shape default
): 
\newline
 This subroutine calculates the radius-of-gyration 'rgy' and the end-to-end
 distance 'ee' for the protein molecule 'nml'.
 Both quantities characterize the compactness of a protein conformation.
 
\end_layout

\begin_layout Subsubsection
Function RMSDFUN
\begin_inset LatexCommand index
name "RMSDFUN"

\end_inset


\end_layout

\begin_layout Standard
(Usage: 
\shape italic
rmsd = rmsdfun(nml,ir1,ir2,ixat,xrf,yrf,zrf,isl)
\shape default
)
\newline
 The real*8 function '
\shape italic
rmsdfun
\shape default
' calculates the root-mean square-deviation (rmsd) between atom postions
 in the current configuration of molecule '
\shape italic
nml
\shape default
' for a range of residues '
\shape italic
[ir1,ir2]
\shape default
' and a reference structure given by arrays of atom coordinates '
\shape italic
xrf,yrf,zrf
\shape default
'.
 For each atom position in the current SMMP-structure the array '
\shape italic
ixat
\shape default
' provides the index of the equivalent atom in the reference structure,
 or yields a value of '
\shape italic
0
\shape default
' if there is no equivalent.
 By setting '
\shape italic
isl=0
\shape default
' the rmsd is calculated over all non-hydrogen (heavy) atoms, for '
\shape italic
isl = 1
\shape default
' for backbone atoms only, and for '
\shape italic
isl = 2
\shape default
' the rmsd is calculated only between C
\begin_inset Formula $^{\alpha}$
\end_inset

-atoms.
 The routine '
\shape italic
rmsdfun
\shape default
' may only be called 
\series bold
after
\series default
 an initial call of the subroutine '
\shape italic
rmsinit(nml,string)
\shape default
'.
 If 
\shape italic
string = 'smmp'
\shape default
 the reference configuration is a SMMP configuration, otherwise it is read
 in from a PDB-file which name given by '
\shape italic
string
\shape default
'.
 
\end_layout

\begin_layout Subsubsection
Subroutine ZIMMER
\begin_inset LatexCommand index
name "ZIMMER"

\end_inset


\end_layout

\begin_layout Standard
(Usage: 
\shape italic
call zimmer(nresi)
\shape default
):
\newline
 This subroutine analyzes the backbone dihedrals of a given conformation
 and characterizes the state of each pair of (
\begin_inset Formula $\phi,\psi$
\end_inset

) by its Zimmerman code.
 The subroutine requires as input the number of residues 'nresi' and returns
 the character string 'zimm' with the Zimmerman code of the present configuratio
n (through a common block).
 
\end_layout

\begin_layout Section
How to cite SMMP
\end_layout

\begin_layout Standard
Use of SMMP should be acknowledged by quoting the following reference: F.
 Eisenmenger, U.H.E.
 Hansmann, Sh.
 Hayryan, C.-K.
 Hu, 
\series bold
[SMMP] A Modern Package for Simulation of Proteins
\series default
, 
\shape italic
Comp.
 Phys.
 Comm.

\shape default
 
\series bold
138
\series default
 (2001) 192-212;
\newline
F.
 Eisenmenger, U.H.E.
 Hansmann, Sh.
 Hayryan, C.-K.
 Hu, 
\series bold
An Enhanced Version of SMMP - Open-Source Software Package for Simulation
 of Proteins
\series default
, 
\shape italic
Comp.Phys.
 Comm.
 174 (2006) 422-
\shape default
429; 
\newline

\emph on
J.
 H.
 Meinke, S.
 Mohanty, F.
 Eisenmenger and U.H.E.
 Hansmann,
\series bold
\emph default
 SMMP v.
 3.0 --- Simulating proteins and protein interactions in Python and Fortran
\series default
, submitted to 
\emph on
Comp.\InsetSpace ~
Phys.\InsetSpace ~
Comm.
\newline

\emph default
Where appropriate, the program package's web-site should be quoted as: 
\series bold
SMMP, 
\begin_inset LatexCommand url
target "http://www.phy.mtu.edu/biophys/smmp.htm"

\end_inset

 or 
\series default

\begin_inset LatexCommand url
target "http://www.smmp05.net"

\end_inset

.
 
\end_layout

\begin_layout Section
Examples
\begin_inset LatexCommand label
name "sec:Examples"

\end_inset


\end_layout

\begin_layout Standard
All the examples can be found in the EXAMPLES subdirectory and should be
 run from there.
 All the serial examples can be built either from the top-level directory
 with 
\emph on
make examples
\emph default
 or from within the EXAMPLES directory with 
\emph on
make
\emph default
.
 The MPI parallel tempering example is built from within the EXAMPLES directory
 with 
\emph on
make parallel_tempering_p.

\emph default
 The structure of all examples is very similar to Listing 
\begin_inset LatexCommand ref
reference "listing:mainmc"

\end_inset

.
 We first initialize the force field we want to use, load the protein either
 from a sequence and a configuration file or from a PDB file, set the simulation
 parameters, and finally call the simulation subroutine.
 We use
\shape italic
\emph on
 
\emph default
grpn = 'nh2', grpc = 'cooh'
\emph on
 as end groups in all of our examples.
 We also use a fixed value for the dielectric constant, so that 
\emph default
epsd=.false.

\emph on
 in all cases.
\end_layout

\begin_layout Standard
The first example 
\begin_inset LatexCommand eqref
reference "sub:Minimization-of-vacuum"

\end_inset

 minimizes the energy of met-enkaphalin, a small endorphin with only 5 amino
 acids using a quasi-newton minimizer.
 The second examples 
\begin_inset LatexCommand eqref
reference "sub:Structure-Determination-by"

\end_inset

 tries to find the minimum vacuum energy structure of met-enkaphalin using
 simulated annealing.
 The third example 
\begin_inset LatexCommand eqref
reference "sub:Calculation-of-Multicanonical"

\end_inset

 shows how to calculate the estmated weights necessary for a multi-canonical
 Monte Carlo simulation.
 Met-enkaphalin again serves as sample system.
 In 
\begin_inset LatexCommand eqref
reference "sub:Regularization-of-the"

\end_inset

 we show how to regularize an experimental structure read from a PDB file.
 The force fields implemented use fixed bond lengths and valence angles.
 Without regularization, a structure read from a PDB file often has an unreasona
bly high energy.
 Finally, we show how to perform parallel tempering simulations on multiple
 processors 
\begin_inset LatexCommand eqref
reference "sub:Parallel-Tempering-simulation"

\end_inset

 and on a single processor 
\begin_inset LatexCommand eqref
reference "sub:Parallel-tempering-on"

\end_inset

.
 The sample output was generated on a system with two dual-core AMD Opteron
 2216 processor running SUSE LINUX 10.1 (X86-64).
 The programs were compiled with Intels Fortran compiler with optimization
 set to -O2.
\end_layout

\begin_layout Subsection
Minimization of vacuum energy from a given configuration
\begin_inset LatexCommand label
name "sub:Minimization-of-vacuum"

\end_inset


\end_layout

\begin_layout Standard
The MAIN module in minimization.f, has the following settings: 
\newline

\shape italic
\emph on
ientyp = 0
\newline
sh2 = .false.
 
\newline
itysol = 0
\newline
iabin = 1
\shape default
,
\newline

\emph default

\newline
 which restrict energy calculations to evaluation of the ECEPP/3 energy
 (no protein-solvent interactions taken into account), choses 
\shape italic
nh2
\shape default
 as N-terminal group and at the C-terminus the 
\shape italic
cooh
\shape default
-group, and the input is read from a sequence/configuration file.
 The simulation task subroutine is called with
\newline
imin = 1
\newline
maxit=10000
\newline
eps=1.0d-9
\newline

\shape italic
call minim(imin,mait,eps)
\shape default
,
\newline
 i.e.
 the simulation task is the local minimization of the vacuum energy of a
 configuration using the Quasi-Newton algorithm.
 Compile the program with 
\emph on
make minimization
\emph default
, SMMP with this default settings will minimize the configuration given
 in 
\shape italic
enkefa.var
\shape default
.
 Running minimization from the EXAMPLES directory will lead to the following
 output: 
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

init_energy: itysol =            0  
\end_layout

\begin_layout Standard

init_energy: esol_scaling =  F  
\end_layout

\begin_layout Standard

init_molecule: Solvent:            0  
\end_layout

\begin_layout Standard

File with sequence is enkefa.seq  
\end_layout

\begin_layout Standard

addend> Net charge of molecule # 1:   0.001
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

enkefa.var
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    1 Tyr : x1  set   -172.590
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    1 Tyr : x2  set     78.710  
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    1 Tyr : x6  set   -165.880 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    1 Tyr : phi set    -86.240
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    2 Gly : psi set    156.180
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    2 Gly : omg set   -180.000 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    2 Gly : phi set   -154.530 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    3 Gly : psi set     83.640 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    3 Gly : omg set    180.000 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    3 Gly : phi set     83.660 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    4 Phe : psi set    -73.860 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    4 Phe : omg set   -180.000 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    4 Phe : x1  set     58.790 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    4 Phe : x2  set     94.600 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    4 Phe : phi set   -137.040 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    5 Met : psi set     19.330 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    5 Met : omg set   -180.000 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    5 Met : x1  set     52.760 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    5 Met : x2  set    175.280 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    5 Met : x3  set   -179.830 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    5 Met : x4  set    -58.570 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    5 Met : phi set   -163.630 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    5 Met : pst set    160.450 
\end_layout

\begin_layout Standard

redvar> Met-Enkephalin: residue    5 Met : omt set    180.000
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

Energy BEFORE minimization:
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

Total:  0.10354E+04    
\end_layout

\begin_layout Standard

  Coulomb:  0.1991E+02 Lennard-Jones: 0.1142E+03 HB:  0.9008E+03    
\end_layout

\begin_layout Standard

  Variables:  0.4511E+00  Solvatation:  0.0000E+00
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

Step     1: energy  0.489976E+05  ( 0.867243E+13 )  
\end_layout

\begin_layout Standard

Step     2: energy  0.108241E+03  ( 0.964364E+07 )  
\end_layout

\begin_layout Standard

Step     3: energy -0.632755E+00  ( 0.498256E+04 )  
\end_layout

\begin_layout Standard

Step     4: energy -0.739539E+01  ( 0.109979E+05 )  
\end_layout

\begin_layout Standard

Step     5: energy  0.517957E+03  ( 0.678892E+09 )  
\end_layout

\begin_layout Standard

Step     6: energy -0.767774E+01  ( 0.143880E+05 )  
\end_layout

\begin_layout Standard

Step     7: energy -0.818570E+01  ( 0.100364E+05 )  
\end_layout

\begin_layout Standard

Step     8: energy -0.938401E+01  ( 0.172508E+04 )  
\end_layout

\begin_layout Standard

Step     9: energy -0.109799E+02  ( 0.105718E+04 )  
\end_layout

\begin_layout Standard

Step    10: energy -0.116244E+02  ( 0.580821E+03 )  
\end_layout

\begin_layout Standard

Step    11: energy -0.116969E+02  ( 0.145676E+04 )  
\end_layout

\begin_layout Standard

Step    12: energy -0.118569E+02  ( 0.856882E+03 )  
\end_layout

\begin_layout Standard

Step    13: energy -0.119576E+02  ( 0.521381E+03 )  
\end_layout

\begin_layout Standard

Step    14: energy -0.120897E+02  ( 0.398602E+03 )  
\end_layout

\begin_layout Standard

Step    15: energy -0.121476E+02  ( 0.222201E+03 )  
\end_layout

\begin_layout Standard

...
\end_layout

\begin_layout Standard

...
\end_layout

\begin_layout Standard

...
\end_layout

\begin_layout Standard

Step    70: energy -0.124285E+02  ( 0.194869E-04 )  
\end_layout

\begin_layout Standard

Step    71: energy -0.124285E+02  ( 0.120524E-04 )  
\end_layout

\begin_layout Standard

Step    72: energy -0.124285E+02  ( 0.641640E-05 )  
\end_layout

\begin_layout Standard

Step    73: energy -0.124285E+02  ( 0.182141E-05 )  
\end_layout

\begin_layout Standard

Step    74: energy -0.124285E+02  ( 0.219308E-05 )  
\end_layout

\begin_layout Standard

Step    75: energy -0.124285E+02  ( 0.348349E-05 )  
\end_layout

\begin_layout Standard

Step    76: energy -0.124285E+02  ( 0.166901E-05 )  
\end_layout

\begin_layout Standard

Step    77: energy -0.124285E+02  ( 0.177102E-06 )  
\end_layout

\begin_layout Standard

Step    78: energy -0.124285E+02  ( 0.663522E-08 )  
\end_layout

\begin_layout Standard

Step    79: energy -0.124285E+02  ( 0.210693E-08 )  
\end_layout

\begin_layout Standard

Step    80: energy -0.124285E+02  ( 0.370905E-08 )  
\end_layout

\begin_layout Standard

Step    81: energy -0.124285E+02  ( 0.324300E-08 )  
\end_layout

\begin_layout Standard

Step    82: energy -0.124285E+02  ( 0.777363E-09 )  
\end_layout

\begin_layout Standard

Step    83: energy -0.124285E+02  ( 0.443358E-10 )  
\end_layout

\begin_layout Standard

Step    84: energy -0.124285E+02  ( 0.322695E-11 )  
\end_layout

\begin_layout Standard

Step    85: energy -0.124285E+02  ( 0.144369E-11 )  
\end_layout

\begin_layout Standard

Step    86: energy -0.124285E+02  ( 0.291517E-11 )  
\end_layout

\begin_layout Standard

Step    87: energy -0.124285E+02  ( 0.322695E-11 )  
\end_layout

\begin_layout Standard

---- CONVERGENCE ----
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

Final energies __________________________________________________
\end_layout

\begin_layout Standard

Total: -0.12429E+02    
\end_layout

\begin_layout Standard

  Coulomb:  0.2143E+02 Lennard-Jones: -0.2923E+02 HB: -0.6706E+01
\end_layout

\begin_layout Standard

  Variables:  0.2084E+01  Solvatation:  0.0000E+00
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

Variables _________________
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

x1     1  -173.2    (  0.6)  
\end_layout

\begin_layout Standard

x2     1    79.3    (  0.6)  
\end_layout

\begin_layout Standard

x6     1  -166.3    (  0.5)  
\end_layout

\begin_layout Standard

phi    1   -83.1    (  3.2)  
\end_layout

\begin_layout Standard

psi    2   155.8    (  0.4)  
\end_layout

\begin_layout Standard

omg    2  -177.1    (  2.9)  
\end_layout

\begin_layout Standard

phi    2  -154.2    (  0.3)  
\end_layout

\begin_layout Standard

psi    3    85.8    (  2.2)  
\end_layout

\begin_layout Standard

omg    3   168.5    ( 11.5)  
\end_layout

\begin_layout Standard

phi    3    83.0    (  0.7)  
\end_layout

\begin_layout Standard

psi    4   -75.0    (  1.2)  
\end_layout

\begin_layout Standard

omg    4  -170.0    ( 10.0)  
\end_layout

\begin_layout Standard

x1     4    58.9    (  0.1)  
\end_layout

\begin_layout Standard

x2     4    94.5    (  0.1)  
\end_layout

\begin_layout Standard

phi    4  -136.8    (  0.2)  
\end_layout

\begin_layout Standard

psi    5    19.1    (  0.2)  
\end_layout

\begin_layout Standard

omg    5  -174.1    (  5.9)  
\end_layout

\begin_layout Standard

x1     5    52.9    (  0.1)  
\end_layout

\begin_layout Standard

x2     5   175.3    (  0.0)  
\end_layout

\begin_layout Standard

x3     5  -179.9    (  0.0)  
\end_layout

\begin_layout Standard

x4     5   -58.6    (  0.0)  
\end_layout

\begin_layout Standard

phi    5  -163.4    (  0.2)  
\end_layout

\begin_layout Standard

pst    5   160.8    (  0.3)  
\end_layout

\begin_layout Standard

omt    5  -179.8    (  0.2)
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

Gradient______________________________________________________________ 
    
\end_layout

\begin_layout Standard

0.000    0.000    0.000    0.000    0.000    0.000    0.000    0.000
\end_layout

\begin_layout Standard

0.000    0.000    0.000    0.000    0.000    0.000    0.000    0.000   
\end_layout

\begin_layout Standard

0.000    0.000    0.000    0.000    0.000    0.000    0.000    0.000 
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset


\end_layout

\begin_layout Subsection
Structure Determination by Simulated Annealing
\begin_inset LatexCommand label
name "sub:Structure-Determination-by"

\end_inset


\end_layout

\begin_layout Standard
For the following simulated annealing run for Met-Enkephalin defined through
 its sequence file 
\shape italic
enkefa.seq
\shape default
, another configuration file 
\shape italic
enkefa.ann
\shape default
 is used.
 In this configuration file the dihedral angles 
\shape italic
omg
\shape default
 and 
\shape italic
omt
\shape default
 are fixed at 180.0 degrees using 
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

om*:  180.0 & 
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

.
 Simulated annealing performs only poorly when these angles are free to
 change.
 In this example we choose ECEPP/2 ( setting 
\shape italic
sh2 = .true.

\shape default
 and no protein-solvation interaction.
 Hence, we have the following settings for parameters in 
\shape italic
annealing.f
\shape default
: 
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

ientyp = 0
\end_layout

\begin_layout Standard

sh2 = .true.
 
\end_layout

\begin_layout Standard

itysol = 0 
\end_layout

\begin_layout Standard

iabin = 1
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

.
 Our simulated annealing run consists of 100 Monte Carlo sweeps at the highest
 temperature (1000 K) followed by 100,000 sweeps during which the temperature
 is gradually decreased to a final temperature of 100 K.
 The progress of the simulation is monitored by writing data into the file
 `
\shape italic
time.d
\shape default
' every 1000 sweeps.
 The simulation starts from a random configuration.
 
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

lrand=.true.
 
\end_layout

\begin_layout Standard

nequi=100, 
\end_layout

\begin_layout Standard

nswp=100000
\end_layout

\begin_layout Standard

nmes=1000 
\end_layout

\begin_layout Standard

tmax=1000.0
\end_layout

\begin_layout Standard

tmin=100.0
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

call anneal(nequi, nsweeps, nmes, tmax, tmin, lrand)
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset


\end_layout

\begin_layout Standard
After compiling the example with 
\emph on
make annealing
\emph default
 in the sub-directory 
\shape italic
EXAMPLES,
\shape default
 
\shape italic
\emph on
we run the program by calling
\shape default
\emph default
 
\shape italic
annealing.

\shape default
 The output will contain the energy of the start configuration, energy after
 equilibration, the average acceptance rate of moves in the simulated annealing
 run, the final configuration (and its energy) and the configuration with
 the lowest energy found in this run: 
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

 init_energy: itysol =            0  
\end_layout

\begin_layout Standard

 init_energy: esol_scaling =  F  
\end_layout

\begin_layout Standard

 init_molecule: Solvent:            0 
\end_layout

\begin_layout Standard

 File with SEQUENCE: enkefa.seq
\end_layout

\begin_layout Standard

 enkefa.ann
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

 redvar> Met-Enkephalin: residue    2 Gly : omg set    180.000   Fixed
\end_layout

\begin_layout Standard

 redvar> Met-Enkephalin: residue    3 Gly : omg set    180.000   Fixed
\end_layout

\begin_layout Standard

 redvar> Met-Enkephalin: residue    4 Phe : omg set    180.000   Fixed
\end_layout

\begin_layout Standard

 redvar> Met-Enkephalin: residue    5 Met : omg set    180.000   Fixed
\end_layout

\begin_layout Standard

 redvar> Met-Enkephalin: residue    5 Met : omt set    180.000   Fixed
\end_layout

\begin_layout Standard

 redvar> Molecule Met-Enkephalin:    19 variable(s) remain unchanged
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

energy of start configuration:  0.75921E+09
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

 Energy after  equilibration:   11.0835755006373 
\end_layout

\begin_layout Standard

 acceptance rate:  0.181430817270775
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

 last energy  -8.03108763810183
\end_layout

\begin_layout Standard

      1 :   1 : x1  :   -168.428
\end_layout

\begin_layout Standard

      1 :   1 : x2  :     89.562
\end_layout

\begin_layout Standard

      1 :   1 : x6  :     -2.861
\end_layout

\begin_layout Standard

      1 :   1 : phi :   -112.654
\end_layout

\begin_layout Standard

      1 :   2 : psi :    156.420
\end_layout

\begin_layout Standard

      1 :   2 : omg :   -180.000  &
\end_layout

\begin_layout Standard

      1 :   2 : phi :   -174.567
\end_layout

\begin_layout Standard

      1 :   3 : psi :    146.718
\end_layout

\begin_layout Standard

      1 :   3 : omg :   -180.000  &
\end_layout

\begin_layout Standard

      1 :   3 : phi :     68.148
\end_layout

\begin_layout Standard

      1 :   4 : psi :    -96.563
\end_layout

\begin_layout Standard

      1 :   4 : omg :   -180.000  &
\end_layout

\begin_layout Standard

      1 :   4 : x1  :     59.864
\end_layout

\begin_layout Standard

      1 :   4 : x2  :    -83.907
\end_layout

\begin_layout Standard

      1 :   4 : phi :   -141.914
\end_layout

\begin_layout Standard

      1 :   5 : psi :     20.747
\end_layout

\begin_layout Standard

      1 :   5 : omg :   -180.000  &
\end_layout

\begin_layout Standard

      1 :   5 : x1  :     61.133
\end_layout

\begin_layout Standard

      1 :   5 : x2  :   -174.118
\end_layout

\begin_layout Standard

      1 :   5 : x3  :    176.917
\end_layout

\begin_layout Standard

      1 :   5 : x4  :   -178.096
\end_layout

\begin_layout Standard

      1 :   5 : phi :   -162.246
\end_layout

\begin_layout Standard

      1 :   5 : pst :    161.616
\end_layout

\begin_layout Standard

      1 :   5 : omt :   -180.000  &
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

 lowest energy ever found:       63297  -9.40635361798398 
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

 The random start configuration, final configuration and lowest-energy configura
tion are also written in PDB-format into the files 
\shape italic
start.pdb
\shape default
, 
\shape italic
final.pdb
\shape default
 and 
\shape italic
global.pdb
\shape default
 allowing for easy visualization of these configurations with programs graphical
ly displaying PDB-structures.
 The progress of the simulated annealing run is monitored through the time
 series in file 
\shape italic
time.d
\shape default
 which list the Monte Carlo sweep, temperature, ECEPP/2 energy, radius-of-gyrati
on, the partial energy terms 
\begin_inset Formula $E_{\mbox{hb}}$
\end_inset

, 
\begin_inset Formula $E_{\mbox{vdW}}$
\end_inset

, 
\begin_inset Formula $E_{\mbox{C}}$
\end_inset

, 
\begin_inset Formula $E_{\mbox{vr}}$
\end_inset

and the Zimmerman-coding of the present configuration.
 All the terms related to the solvent have been replaced by a single dot
 per column in the sample below.
 
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

 # $Id: anneal.f 192 2007-01-02 14:06:25Z meinke $
\end_layout

\begin_layout Standard

 # nsw, temp, eol, eysl, eyslh, eyslp, asa, rgy, 
\end_layout

\begin_layout Standard

 # rgyh, rgyp, eyhb, eyvw, eyel, eyvr, zimm
\end_layout

\begin_layout Standard

     0 1000.000  8.045 ....
 4.542 ..
 -3.992 -14.929 23.308 3.658 ghcBD
\end_layout

\begin_layout Standard

  1000  977.237 16.397 ....
 5.835 ..
 -2.029 -11.821 24.061 6.186 BDeCG
\end_layout

\begin_layout Standard

  2000  954.993 16.147 ....
 5.302 ..
 -1.786 -11.072 25.230 3.775 AdEDA
\end_layout

\begin_layout Standard

  3000  933.254 26.320 ....
 6.434 ..
 -1.324  -4.642 25.514 6.771 EecFC
\end_layout

\begin_layout Standard

  4000  912.011 14.884 ....
 5.145 ..
 -2.474 -13.559 25.449 5.469 EHDDB
\end_layout

\begin_layout Standard

  5000  891.251 21.650 ....
 5.882 ..
 -1.179  -8.380 27.125 4.083 EHfEB
\end_layout

\begin_layout Standard

  6000  870.964 13.854 ....
 5.806 ..
 -2.271 -12.703 25.621 3.207 EcaEh
\end_layout

\begin_layout Standard

  7000  851.138 19.786 ....
 5.439 ..
 -1.952  -9.254 26.428 4.565 EHaAE
\end_layout

\begin_layout Standard

  8000  831.764 14.299 ....
 5.986 ..
 -1.596 -16.538 24.699 7.735 EECEF
\end_layout

\begin_layout Standard

  9000  812.831  7.773 ....
 4.915 ..
 -2.819 -16.392 24.850 2.134 EECBB
\end_layout

\begin_layout Standard

...
\end_layout

\begin_layout Standard

...
\end_layout

\begin_layout Standard

...
\end_layout

\begin_layout Standard

 91000  123.027 -8.381 ....
 4.414 ..
 -5.162 -26.932 22.230 1.483 FEcDE
\end_layout

\begin_layout Standard

 92000  120.226 -6.302 ....
 4.439 ..
 -4.825 -25.727 22.824 1.426 EEcDE
\end_layout

\begin_layout Standard

 93000  117.490 -6.655 ....
 4.413 ..
 -4.355 -25.081 21.937 0.845 FEcDE
\end_layout

\begin_layout Standard

 94000  114.815 -8.190 ....
 4.523 ..
 -6.848 -24.025 21.598 1.086 FEcDE
\end_layout

\begin_layout Standard

 95000  112.202 -5.965 ....
 4.434 ..
 -5.052 -24.021 21.995 1.114 EEcDE
\end_layout

\begin_layout Standard

 96000  109.648 -7.081 ....
 4.444 ..
 -4.717 -25.137 22.669 0.104 EEcDE
\end_layout

\begin_layout Standard

 97000  107.152 -8.042 ....
 4.561 ..
 -4.969 -25.544 21.850 0.621 FEcDE
\end_layout

\begin_layout Standard

 98000  104.713 -7.342 ....
 4.439 ..
 -4.737 -26.152 22.463 1.083 FEcDE
\end_layout

\begin_layout Standard

 99000  102.329 -6.561 ....
 4.438 ..
 -3.975 -25.213 21.963 0.664 FEcDE
\end_layout

\begin_layout Standard

100000  100.000 -8.031 ....
 4.433 ..
 -5.231 -25.792 22.659 0.333 EEcDE
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset


\end_layout

\begin_layout Subsection
Calculation of Multicanonical Parameters
\begin_inset LatexCommand label
name "sub:Calculation-of-Multicanonical"

\end_inset


\end_layout

\begin_layout Standard
In the following example, multicanonical parameters are calculated for met-enkep
halin (with fixed omega angles) in gas-phase simulations relying on the
 ECEPP/3 force-field.
 
\shape italic
\emph on
The functions
\shape default
\emph default
 
\shape italic
mulcan_par
\shape default
 
\shape italic
\emph on
and
\shape default
\emph default
 
\shape italic
mulcan_sim
\shape default
 are part of the module 
\emph on
multicanonical.

\emph default
 To use the module, include 
\emph on
use multicanonical
\emph default
 in 
\emph on
main
\emph default
.
 For this example, we set the following parameters in '
\shape italic
main
\shape default
': 
\end_layout

\begin_layout Standard
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

ientyp = 0
\end_layout

\begin_layout Standard

sh2 = .false.
 
\end_layout

\begin_layout Standard

itysol = 0 
\end_layout

\begin_layout Standard

iabin = 1
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

 
\end_layout

\begin_layout Standard
The simulation has a total of 100,000 Monte Carlo sweeps and the multicanonical
 parameters are updated every 2,000 sweeps.
 The parameters are calculated from scratch, and we attempt to obtain a
 histogram in energy in the interval [-12,20] Kcal/mol with energy bin size
 1 Kcal/mol.
 We expect that at temperature 1000 K we are clearly in the high-energy
 phase where successive configurations have little correlation.
 This leads to the following set of arguments for calling 
\emph on
mulcan
\emph default
_
\emph on
par
\emph default
: 
\end_layout

\begin_layout Standard
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

l_iter=.false.
\end_layout

\begin_layout Standard

kmin=-12
\end_layout

\begin_layout Standard

kmax=20
\end_layout

\begin_layout Standard

ebin=1.0d0
\end_layout

\begin_layout Standard

nsweep=100000
\end_layout

\begin_layout Standard

nup=5000
\end_layout

\begin_layout Standard

temp=1000.0
\end_layout

\begin_layout Standard

call mulcan_par(nsweep, nup, temp, kmin, kmax, l_iter)
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

 
\end_layout

\begin_layout Standard
This example is available in the file 
\emph on
multicanonical.f
\emph default
 in the EXAMPLES directory.
 After compiling it with 
\emph on
make
\emph default
 
\emph on
multicanonical
\emph default
 and running the program using 
\emph on
multicanonical
\emph default
 the calculated multicanonical parameters are written into the file '
\shape italic
muca.d
\shape default
'.
 For further iteration of these parameters additional quantities such as
 the accumulated histogram are written into a file '
\shape italic
mpar_full.d
\shape default
' (out of which '
\shape italic
mulcan_par
\shape default
' reads them if '
\shape italic
l_iter=.true.
\shape default
' is set).
 We show here only the file '
\shape italic
muca.d
\shape default
' which lists the index of the energy bin, the 
\begin_inset Formula $\beta(E)$
\end_inset

 and the 
\begin_inset Formula $\alpha(E)$
\end_inset

 parameters (see 
\begin_inset LatexCommand citep
key "Eisenmenger2001"

\end_inset

) for more detailed explanations and references on multicanonical simulations):
\end_layout

\begin_layout Standard
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

-12   11.8671041270715        93.0982188015155     
\end_layout

\begin_layout Standard

-11   6.74942546567488        34.2449141954539     
\end_layout

\begin_layout Standard

-10   4.76239638525333        13.3811088510276     
\end_layout

\begin_layout Standard

 -9   2.62566106761319       -6.91787666655369     
\end_layout

\begin_layout Standard

 -8   2.76891298156071       -5.70023539799973     
\end_layout

\begin_layout Standard

 -7   2.98636199792932       -4.06936777523520     
\end_layout

\begin_layout Standard

 -6   2.62458524605883       -6.42091666239336     
\end_layout

\begin_layout Standard

 -5   2.68953283146133       -6.06370494267963     
\end_layout

\begin_layout Standard

 -4   1.99405651648455       -9.19334836007513     
\end_layout

\begin_layout Standard

 -3   2.37207855308226       -7.87027123198313     
\end_layout

\begin_layout Standard

 -2   1.80430850778520       -9.28969634522579     
\end_layout

\begin_layout Standard

 -1   1.91571656031594       -9.12258426642968     
\end_layout

\begin_layout Standard

  0   1.72752866077015       -9.21667821620257     
\end_layout

\begin_layout Standard

  1   1.66881722525666       -9.18732249844583     
\end_layout

\begin_layout Standard

  2   1.50004119691055       -8.93415845592665     
\end_layout

\begin_layout Standard

  3   1.39142908670518       -8.66262818041324     
\end_layout

\begin_layout Standard

  4   1.16605491925085       -7.87381859432308     
\end_layout

\begin_layout Standard

  5   1.88002935687926       -11.0867035636509     
\end_layout

\begin_layout Standard

  6  0.784923700785834       -5.06362245513708     
\end_layout

\begin_layout Standard

  7   1.15928001690741       -7.49693850992732     
\end_layout

\begin_layout Standard

  8   1.53630835441332       -10.3246510412217     
\end_layout

\begin_layout Standard

  9  0.804876443148135       -4.10747979546758     
\end_layout

\begin_layout Standard

 10   1.20439627142663       -7.90291816411324     
\end_layout

\begin_layout Standard

 11  0.843296201282429       -4.11136742759918     
\end_layout

\begin_layout Standard

 12   1.03327436670481       -6.29611632995659     
\end_layout

\begin_layout Standard

 13  0.847836723791197       -3.97814579353639     
\end_layout

\begin_layout Standard

 14  0.794466332096526       -3.25764550565833     
\end_layout

\begin_layout Standard

 15  0.665347460625295       -1.38542186932548     
\end_layout

\begin_layout Standard

 16  0.897108190646473       -4.97771318465375     
\end_layout

\begin_layout Standard

 17  0.527634627532446        1.11860060672770     
\end_layout

\begin_layout Standard

 18  0.591554662202600       0.000000000000000E+000
\end_layout

\begin_layout Standard

 19  0.591554662202600       0.000000000000000E+000
\end_layout

\begin_layout Standard

 20  0.591554662202600       0.000000000000000E+000
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

 
\end_layout

\begin_layout Standard
A test simulation of 100,000 Monte Carlo sweeps (using subroutine '
\shape italic
mulcan_sim
\shape default
' with these weights led to the following histogram that is flat over the
 studied energy range (as is characteristic for the multicanonical ensemble)
 (note that the last energy bin contains all entries for energies larger/equal
 than 20 Kcal/mol): 
\end_layout

\begin_layout Standard
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

-9    105
\end_layout

\begin_layout Standard

-8    828
\end_layout

\begin_layout Standard

-7   1945
\end_layout

\begin_layout Standard

-6   3108
\end_layout

\begin_layout Standard

-5   3247
\end_layout

\begin_layout Standard

-4   3054
\end_layout

\begin_layout Standard

-3   2844
\end_layout

\begin_layout Standard

-2   2531
\end_layout

\begin_layout Standard

-1   2397
\end_layout

\begin_layout Standard

 0   2082
\end_layout

\begin_layout Standard

 1   2179
\end_layout

\begin_layout Standard

 2   2294
\end_layout

\begin_layout Standard

 3   2579
\end_layout

\begin_layout Standard

 4   3193
\end_layout

\begin_layout Standard

 5   2855
\end_layout

\begin_layout Standard

 6   2927
\end_layout

\begin_layout Standard

 7   3994
\end_layout

\begin_layout Standard

 8   3362
\end_layout

\begin_layout Standard

 9   3047
\end_layout

\begin_layout Standard

10   3289
\end_layout

\begin_layout Standard

11   3199
\end_layout

\begin_layout Standard

12   3412
\end_layout

\begin_layout Standard

13   3034
\end_layout

\begin_layout Standard

14   3092
\end_layout

\begin_layout Standard

15   3258
\end_layout

\begin_layout Standard

16   3079
\end_layout

\begin_layout Standard

17   2957
\end_layout

\begin_layout Standard

18   3157
\end_layout

\begin_layout Standard

19   3055
\end_layout

\begin_layout Standard

20  19897
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset


\end_layout

\begin_layout Subsection
Regularization of the B domain of protein A
\begin_inset LatexCommand label
name "sub:Regularization-of-the"

\end_inset


\end_layout

\begin_layout Standard
Frequently, one wants to compare the results of a simulation with experimental
 data.
 When we compare properties of calculated configurations with those of structure
s from the Protein Data Bank (PDB), we have to remember that the actual
 bond lengths and angles in the PDB-structure will differ from the fixed
 values that are assumed with the ECEPP, FLEX, and Lund potentials.
 Forcing the molecule into the standard bonding geometry model may lead
 to un-physically high energies.
 The process of finding an optimal structure within the standard geometry
 model starting from a PDB-structure is called regularization.
\end_layout

\begin_layout Standard
In our example, we regularize of the coordinates for residues 10-55 of the
 B domain of 
\shape italic
Staphylococcus Aureus
\shape default
 Protein A, which were taken from entry 
\shape italic
1BDD
\shape default
 of the Protein Data Bank (see 
\begin_inset LatexCommand url
target "http://www.rcsb.org"

\end_inset

), as provided with this package in file 
\shape italic
1bdd.pdb
\shape default
.
 Setting the variable '
\shape italic
iabin = 0
\shape default
' in 
\shape italic
main.f
\shape default
 makes 
\shape italic
init_molecule
\shape default
 call subroutine 
\shape italic
pdbread
\shape default
 that reads the amino acid sequence and the atomic coordinates from the
 PDB- structure and stores this data in arrays declared in '
\shape italic
INCP.H
\shape default
'.
 Then 
\shape italic
pdbvars
\shape default
 is automatically called to measure all dihedral angles.
 In order to regularize the PDB-structure one has to 
\shape italic
call regul(nml, iter, nsteps, 
\begin_inset Formula $\varepsilon$
\end_inset

)
\shape default
 as the task subroutine in '
\shape italic
main
\shape default
' .
 Set the following parameters in '
\shape italic
main
\shape default
', accordingly:
\newline

\newline

\shape italic
ientyp=0
\newline
 sh2 = .false.
\newline
 itysol = 0
\newline
 iabin = 0
\shape default

\newline

\newline
 Note that '
\shape italic
regul
\shape default
', as any other task subroutine, has to be called AFTER '
\shape italic
init_molecule
\shape default
' .
 The example is available in the EXAMPLES directory.
 You can compile it by calling 
\emph on
make regularization.

\emph default
 Run the program by calling 
\emph on
regularization
\emph default
.
 We use 10 iterations with up to 15000 sweeps each and 
\begin_inset Formula $\varepsilon=10^{-7}$
\end_inset

.
 A value for 
\begin_inset Formula $\varepsilon$
\end_inset

 that is too large may lead to numerical instabilities.
 
\end_layout

\begin_layout Standard
First '
\shape italic
regul
\shape default
' obtains its input from the arrays declared in '
\shape italic
INCP.H
\shape default
'.
 In a first step a naive representation of the molecule is build in the
 ECEPP geometry from the stored dihedral angles that were calculated from
 the PDB coordinates.
 This simple model serves as starting configuration for the regularization.
 In our example, its root-mean-square deviation (over all heave atoms) compared
 to the PDB-structure initially is 2.8 
\begin_inset ERT
status collapsed

\begin_layout Standard


\backslash
AA
\end_layout

\end_inset

 and its ECEPP-energy 
\begin_inset Formula $\approx10^{5}$
\end_inset

 kcal/mol, mainly due to excessive van-der-Waals repulsions.
 The regularization starts by first minimizing a term that measures the
 sum of squared distances between heavy atoms in the SMMP-structure and
 the given PDB-structure.
 This leads to a rmsd of 0.14 
\begin_inset ERT
status collapsed

\begin_layout Standard


\backslash
AA
\end_layout

\end_inset

.
 After this initial step a list of bad contacts (vdW-energy of more than
 2 kcal/mol) in the SMMP-structure is printed out.
 In a second step the physical energy is minimized, allowing only the free
 hydrogens to move, and the bad contacts and rmsd are displayed again.
 This step reduces the ECEPP-energy to 
\begin_inset Formula $\approx10^{3}$
\end_inset

 kcal/mol.
 '
\shape italic
Regul
\shape default
' aims at further reducing this energy while at the same time keeping the
 rmsd as small as possible.
 This is done by minimizing a composite energy from the weighted sum of
 physical ECEPP-energy and constraint energy (the quadratic distance measure)
 over 10 iterations.
 In each iteration the weight of the constraint energy is successively lowered
 (from 1 to 0) and the weight of the ECEPP energy raised (from 0 to 1).
 At the end, the dihedral angles of the final structure are printed out
 together with its rmsd and a list of (eventually) remaining bad contacts.
\end_layout

\begin_layout Standard
The following output is obtained from this last iteration with a weight
 of 1 for the ECEPP-energy and a weight of 0 for the constraint energy,
 that leads to a SMMP-configuration with a total ECEPP-energy of 
\begin_inset Formula $-429.9$
\end_inset

 kcal/mol and a rmsd of 1.89 
\begin_inset ERT
status inlined

\begin_layout Standard


\backslash
AA
\end_layout

\end_inset

, compared to the PDB-structure: 
\end_layout

\begin_layout Standard
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

 ================ Minimization #10   Wt(energy) =   0.100E+01  Wt(regul.)
 =   0.000E+00
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

 Energy BEFORE minimization:
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

 Total: -0.39831E+03
\end_layout

\begin_layout Standard

   Coulomb: -0.4685E+02 Lennard-Jones: -0.3306E+03 HB: -0.6915E+02
\end_layout

\begin_layout Standard

   Variables:  0.4831E+02  Solvatation:  0.0000E+00 Regularization:  0.3315E+03
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

 Step     1: energy  0.259565E+13  ( 0.296722E+30, 0.363456E+12 )
\end_layout

\begin_layout Standard

 Step     2: energy  0.481884E+09  ( 0.572102E+22, 0.644342E+12 )
\end_layout

\begin_layout Standard

 Step     3: energy  0.444100E+10  ( 0.599018E+24, 0.617413E+12 )
\end_layout

\begin_layout Standard

 Step     4: energy  0.491253E+10  ( 0.220900E+25, 0.533540E+12 )
\end_layout

\begin_layout Standard

 Step     5: energy -0.355950E+03  ( 0.341264E+06, 0.495213E+10 )
\end_layout

\begin_layout Standard

 Step     6: energy -0.395467E+03  ( 0.762827E+06, 0.726715E+08 )
\end_layout

\begin_layout Standard

 Step     7: energy -0.398489E+03  ( 0.198935E+05, 0.137122E+08 )
\end_layout

\begin_layout Standard

 Step     8: energy -0.398761E+03  ( 0.409017E+05, 0.187175E+08 )
\end_layout

\begin_layout Standard

 Step     9: energy -0.399231E+03  ( 0.197834E+05, 0.329551E+08 )
\end_layout

\begin_layout Standard

 Step    10: energy -0.399787E+03  ( 0.143934E+06, 0.121392E+09 )
\end_layout

\begin_layout Standard

 ...
\end_layout

\begin_layout Standard

 ...
\end_layout

\begin_layout Standard

 ...
\end_layout

\begin_layout Standard

 Step   415: energy -0.429868E+03  ( 0.135007E-03, 0.523386E+11 )
\end_layout

\begin_layout Standard

 Step   416: energy -0.429868E+03  ( 0.123681E-04, 0.523385E+11 )
\end_layout

\begin_layout Standard

 Step   417: energy -0.429868E+03  ( 0.254870E-05, 0.523385E+11 )
\end_layout

\begin_layout Standard

 Step   418: energy -0.429868E+03  ( 0.193334E-05, 0.523385E+11 )
\end_layout

\begin_layout Standard

 Step   419: energy -0.429868E+03  ( 0.140748E-05, 0.523385E+11 )
\end_layout

\begin_layout Standard

 Step   420: energy -0.429868E+03  ( 0.740869E-06, 0.523384E+11 )
\end_layout

\begin_layout Standard

 Step   421: energy -0.429868E+03  ( 0.489693E-06, 0.523384E+11 )
\end_layout

\begin_layout Standard

 Step   422: energy -0.429868E+03  ( 0.282056E-06, 0.523384E+11 )
\end_layout

\begin_layout Standard

 Step   423: energy -0.429868E+03  ( 0.104563E-06, 0.523384E+11 )
\end_layout

\begin_layout Standard

 Step   424: energy -0.429868E+03  ( 0.519142E-07, 0.523385E+11 )
\end_layout

\begin_layout Standard

 Step   425: energy -0.429868E+03  ( 0.104563E-06, 0.523384E+11 )
\end_layout

\begin_layout Standard

 ---- CONVERGENCE ----
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

 Final energies __________________________________________________
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard

 Total: -0.42987E+03
\end_layout

\begin_layout Standard

   Coulomb: -0.5431E+02 Lennard-Jones: -0.3510E+03 HB: -0.7268E+02
\end_layout

\begin_layout Standard

   Variables:  0.4809E+02  Solvatation:  0.0000E+00 Regularization:  0.2241E+05
\end_layout

\begin_layout Standard

 ...
\end_layout

\begin_layout Standard

 
\end_layout

\begin_layout Standard

  RMSD =    1.89099626258629     
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset


\end_layout

\begin_layout Subsection
Parallel Tempering simulation of four A
\begin_inset Formula $\beta_{16-22}$
\end_inset

 peptides
\begin_inset LatexCommand label
name "sub:Parallel-Tempering-simulation"

\end_inset


\end_layout

\begin_layout Standard
In the following example, a parallel tempering simulation of the fragment
 16--22 of Alzheimer's 
\begin_inset Formula $\beta$
\end_inset

-amyloid in solvent.
 It relies on the ECEPP/3 force-field and all dihedral angles are free.
 References for the algorithm can be found in 
\begin_inset LatexCommand cite
key "Eisenmenger2001"

\end_inset

.
 The simulation is performed on a parallel computer on 
\begin_inset Formula $n\times8$
\end_inset

 processors.
 The example is available in the EXAMPLES directory as 
\emph on
parallel_tempering_p
\emph default
.
 Commpile it using 
\emph on
make parallel_tempering
\emph default
.
 Set the following parameters 
\end_layout

\begin_layout Standard
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

num_replica = 8
\end_layout

\begin_layout Standard

ientyp = 0
\end_layout

\begin_layout Standard

sh2=.false.
\end_layout

\begin_layout Standard

itysol=1
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

 
\end_layout

\begin_layout Standard
After initialization, the program calls 
\emph on
init_molecule
\emph default
 once for every molecule.
 Only the last call contains a reference to a variable file.
 It contains the global coordinates for each molecule
\end_layout

\begin_layout Standard
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

@ 1 : 100, 100, 100, 0, 0, 0 
\end_layout

\begin_layout Standard

@ 2 : -100, -100, -100, 0, 0, 0 
\end_layout

\begin_layout Standard

@ 3 : 100, -100, 100, 0, 0, 0 
\end_layout

\begin_layout Standard

@ 4  : 100, -100, -100, 0, 0, 0
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset


\end_layout

\begin_layout Standard
The subroutine reads the distribution of temperatures (in our example 'temperatu
res_abeta') that has to be provided.
\end_layout

\begin_layout Standard
The simulation starts from a stretched configuration with 100 sweeps for
 equilibration.
 The molecule is then studied over 10,000 sweeps on each node, with measurements
 taken every 10 sweep.
 
\end_layout

\begin_layout Standard
Hence the following arguments have to be passed
\end_layout

\begin_layout Standard
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

      nequi=100
\end_layout

\begin_layout Standard

      nswp=10000
\end_layout

\begin_layout Standard

      nmes=10
\end_layout

\begin_layout Standard

      nsave=1000
\end_layout

\begin_layout Standard

      switch=0
\end_layout

\begin_layout Standard

      newsta=.true.
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

 by calling 
\emph on
partem_p(num_replica, nequi, nswp, nmes, nsave, newsta, switch, rep_id,
 partem_comm).
\end_layout

\begin_layout Standard
After compiling with 
\emph on
make parallel_tempering
\emph default
 the program is ready to run.
 Note that you must first execute 
\emph on
make parallel
\emph default
 in the top-level directory.
 We do not provide a script to launch the program since launching it depends
 on the specific MPI installation.
 The data are written into the file '
\shape italic
ts.d
\shape default
'.
 In our case, the data are the sweep, the temperature index, the index of
 the replica this temperature is currently associated, the inverse temperature,
 and energy, radius-of gyration, number of residues that are part of a helix
 or sheet, number of hydrogen bond, total number of contacts and the number
 of contacts that appear also in the reference configuration: 
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

          10           1           1  0.503086435280445     
\end_layout

\begin_layout Standard

   18.5259057594418       -101.020909189261       1.668390368424223E-004
\end_layout

\begin_layout Standard

   153.870626474863                3           4           0
\end_layout

\begin_layout Standard

          10           2           2  0.838477392134076     
\end_layout

\begin_layout Standard

  -21.8597428563679       -112.839132565408       4.398819716124160E-005
\end_layout

\begin_layout Standard

   164.067677362049                0          12           0
\end_layout

\begin_layout Standard

          10           3           3   1.25771608820111     
\end_layout

\begin_layout Standard

  -63.6878966409724       -115.697268416431       7.324283587028595E-005
\end_layout

\begin_layout Standard

   162.383801785309                2           9           0
\end_layout

\begin_layout Standard

          10           4           4   1.43738981508699     
\end_layout

\begin_layout Standard

  -82.2329362395502       -118.850435462771      -2.589501558808733E-005
\end_layout

\begin_layout Standard

   155.367430914339                3           8           0
\end_layout

\begin_layout Standard

          10           5           5   1.67695478426815     
\end_layout

\begin_layout Standard

  -89.8268073782128       -115.511880821486      -1.910806982598894E-004
\end_layout

\begin_layout Standard

   156.197401324212                1          13           0
\end_layout

\begin_layout Standard

          10           6           6   1.82940521920162     
\end_layout

\begin_layout Standard

  -102.200054103571       -119.664523580541      -2.902461830424936E-005
\end_layout

\begin_layout Standard

   158.377278261187                1           7           0
\end_layout

\begin_layout Standard

          10           7           7   1.92017723389483     
\end_layout

\begin_layout Standard

  -92.5898004594444       -111.866857243732       8.412738265616228E-005
\end_layout

\begin_layout Standard

   156.691206902137                2          13           0
\end_layout

\begin_layout Standard

          10           8           8   2.01234574112178     
\end_layout

\begin_layout Standard

  -91.7374330640579       -118.481236403476      -1.450348059239640E-004
\end_layout

\begin_layout Standard

   160.611273802438                0           9           0
\end_layout

\begin_layout Standard

  ...
\end_layout

\begin_layout Standard

  ...
\end_layout

\begin_layout Standard

  ...
\end_layout

\begin_layout Standard

       10000           1           2  0.503086435280445     
\end_layout

\begin_layout Standard

   25.7121801637793       -112.113204586669      -7.981375910951304E-005
\end_layout

\begin_layout Standard

   171.130731978089                0           5           0
\end_layout

\begin_layout Standard

       10000           2           4  0.838477392134076     
\end_layout

\begin_layout Standard

  -83.1513580270155       -119.884471326212      -3.185178277838820E-005
\end_layout

\begin_layout Standard

   179.222034577900                4           5           0
\end_layout

\begin_layout Standard

       10000           3           3   1.25771608820111     
\end_layout

\begin_layout Standard

  -88.7115772801244       -109.660390359632       2.816222447889407E-005
\end_layout

\begin_layout Standard

   169.412616033656                6           2           0
\end_layout

\begin_layout Standard

       10000           4           1   1.43738981508699     
\end_layout

\begin_layout Standard

  -117.230892149812       -118.180458392844      -1.362571932424056E-004
\end_layout

\begin_layout Standard

   155.662046672612                9           3           0
\end_layout

\begin_layout Standard

       10000           5           5   1.67695478426815     
\end_layout

\begin_layout Standard

  -117.452066538358       -114.923193931984       9.292455852280616E-005
\end_layout

\begin_layout Standard

   165.838174859018                8           4           0
\end_layout

\begin_layout Standard

       10000           6           8   1.82940521920162     
\end_layout

\begin_layout Standard

  -114.553279087787       -116.322737335011       1.354655604376923E-005
\end_layout

\begin_layout Standard

   161.094515087733                4           4           0
\end_layout

\begin_layout Standard

       10000           7           7   1.92017723389483     
\end_layout

\begin_layout Standard

  -128.613090309274       -113.083234658370       6.618583172642824E-005
\end_layout

\begin_layout Standard

   169.226190038938               10           0           0
\end_layout

\begin_layout Standard

       10000           8           6   2.01234574112178     
\end_layout

\begin_layout Standard

  -116.001290834057       -115.250965599594       8.095072332381373E-005
\end_layout

\begin_layout Standard

   169.725277983610                8           4           0
\end_layout

\begin_layout Standard

\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset


\end_layout

\begin_layout Standard
At the end of the simulation, the final configurations are written into
 external files (in our case '
\shape italic
conf_00??
\shape default
' where '??' marks the replica index.
 Further information for re-starts are written into '
\shape italic
par_R.in
\shape default
' that also collects statistics on the run.
 
\end_layout

\begin_layout Subsection
Parallel tempering on a serial machine.
\begin_inset LatexCommand label
name "sub:Parallel-tempering-on"

\end_inset


\end_layout

\begin_layout Standard
Parallel tempering is useful even if you have only a single processor machine
 available.
 The algorithm provides better convergence than canonical Monte Carlo and
 avoids the scheduling problems of simulated annealing.
 In this example (see 
\emph on
parallel_tempering_s.f
\emph default
 in the 
\emph on
EXAMPLES
\emph default
 sub directory), we perform a parallel tempering simulation on Met-enkaphalin
 using 5 replicas.
 Each replica runs at a different temperature.
 The temperatures are read in from the file 
\emph on
temperatures
\emph default
.
 The values are 
\end_layout

\begin_layout Standard
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

1 1000
\end_layout

\begin_layout Standard

2 600
\end_layout

\begin_layout Standard

3 400
\end_layout

\begin_layout Standard

4 300
\end_layout

\begin_layout Standard

5 250.
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

 We start the simulation from randomized configurations with 100 sweeps
 for equilibration before we exchange any replicas.
 The main simulation takes 10,000 sweeps with measurements taken every 10
 sweeps.
 An exchange of replicas is also attempted every 10 sweeps.
 This gives us the following variables
\end_layout

\begin_layout Standard
\begin_inset ERT
status open

\begin_layout Standard


\backslash
begin{verbatim}
\end_layout

\begin_layout Standard

num_rep = 5
\end_layout

\begin_layout Standard

nequi = 100       
\end_layout

\begin_layout Standard

nsweep = 10000       
\end_layout

\begin_layout Standard

nmes = 1       
\end_layout

\begin_layout Standard

newsta = .true.
       
\end_layout

\begin_layout Standard

switch = 1
\end_layout

\begin_layout Standard


\backslash
end{verbatim}
\end_layout

\end_inset

 and we call the simulation with
\begin_inset listings
lstparams "breaklines=true,float=h,language=Fortran,showstringspaces=false"
inline false
status collapsed

\begin_layout Standard

call partem_s(num_rep, nequi, nsweep, nmes, nmes, newsta, switch)
\end_layout

\end_inset

The data is written into file 
\emph on
time.d
\emph default
.
 The final configurations are stored in 
\emph on
conf_000?.var
\emph default
, where the question mark is replaced by the replica ID.
\end_layout

\begin_layout Standard
\begin_inset LatexCommand bibtex
options "unsrt"
bibfiles "/home/meinke/research/writeups/bibliography"

\end_inset


\end_layout

\begin_layout Standard
\begin_inset LatexCommand printindex

\end_inset


\end_layout

\end_body
\end_document