[e40e335] | 1 | ! **************************************************************
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| 2 | !
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| 3 | ! This file contains the subroutines: mulcan_par, muca_weight
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| 4 | !
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| 5 | ! Copyright 2003-2005 Frank Eisenmenger, U.H.E. Hansmann,
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| 6 | ! Shura Hayryan, Chin-Ku
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[bd2278d] | 7 | ! Copyright 2007 Frank Eisenmenger, U.H.E. Hansmann,
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| 8 | ! Jan H. Meinke, Sandipan Mohanty
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[e40e335] | 9 | !
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| 10 | ! **************************************************************
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| 11 |
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| 12 | subroutine mulcan_par
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| 13 | !
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| 14 | ! PURPOSE: CALCULATION OF ESTIMATORS FOR MULTICANONICAL WEIGHTS
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| 15 | ! USING A METHOD DESCRIBED FIRST IN: Bernd Berg,
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| 16 | ! {\it J.~Stat.~Phys.} {\bf 82}, 331~(1996). THE METHOD
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| 17 | ! IS STABLE, BUT MAY NOT ALWAYS BE THE FASTEST WAY OF
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| 18 | ! GETTING PARAMETERS
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| 19 | !
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| 20 | ! CALLS: addang,energy,metropolis
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| 21 | !
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| 22 |
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| 23 | include 'INCL.H'
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| 24 |
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| 25 | ! external rand
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| 26 | external muca_weight
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| 27 |
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| 28 | logical l_iter
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| 29 |
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| 30 | parameter(l_iter=.false.)
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| 31 | parameter(kmin=-12,kmax=20,ebin=1.0d0)
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| 32 | parameter(xmin = kmin,xmax=kmax)
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| 33 | parameter(nsweep=100000,nup=5000)
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| 34 | parameter(temp=1000.0)
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| 35 | !
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| 36 | ! l_iter: .true. = for iteration of multicanonical parameters
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| 37 | ! .false. = starts new calculation of multicanonica parameters
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| 38 | ! kmin,kmax: Range of multicanonical parameter
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| 39 | ! ebin: bin size for multicanonical parameter
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| 40 | ! nup: Number of sweeps between updates of multicanonical parameters
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| 41 | ! nsweep: Number of sweeps for simulation run
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| 42 | ! temp: temperature for initial canonical run
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| 43 | !
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| 44 |
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| 45 | dimension xhist(kmin:kmax),g1(kmin:kmax),ent(kmin:kmax)
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| 46 | common/muca/b(kmin:kmax),alpha(kmin:kmax),beta
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| 47 | common/jhist/ihist(kmin:kmax)
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| 48 |
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| 49 |
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| 50 | ! Files with multicanonical parameter
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| 51 | open(11,file='EXAMPLES/mpar_full.d')
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| 52 | open(12,file='EXAMPLES/muca.d')
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| 53 |
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| 54 |
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| 55 | beta=1.0/ ( temp * 1.98773d-3 )
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| 56 | do j=kmin,kmax
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| 57 | ihist(j)= 0
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| 58 | end do
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| 59 |
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| 60 |
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| 61 | if(l_iter) then
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| 62 | ! READ IN FIELDS WITH MULTICANONICAL PARAMETER
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| 63 | Do j=kmin,kmax
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| 64 | read(11,*) i,xhist(i),g1(i),b(i),alpha(i),ent(i)
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| 65 | end do
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| 66 | else
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| 67 | do j=kmin,kmax
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| 68 | b(j) = 0.0d0
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| 69 | alpha(j) = 0.0d0
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| 70 | g1(j) = 0.0d0
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| 71 | xhist(j) = 0.0d0
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| 72 | ent(j) = 0.0d0
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| 73 | end do
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| 74 | end if
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| 75 | !
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| 76 | ! _________________________________ random start
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| 77 | do i=1,nvr
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| 78 | iv=idvr(i) ! provides index of non-fixed variable
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| 79 | dv=axvr(iv)*(grnd()-0.5)
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| 80 | vr=addang(pi,dv)
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| 81 | vlvr(iv)=vr
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| 82 | enddo
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| 83 | !
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| 84 | eol = energy()
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[38d77eb] | 85 | write (logString, '(a,e12.5,/)') 'Energy of start configuration: ',eol
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| 86 | write (logString, *)
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[e40e335] | 87 |
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| 88 | call outpdb(1, 'start.pdb')
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| 89 | !
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| 90 |
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| 91 |
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| 92 | !======================Simulation
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| 93 | acz = 0.0d0
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| 94 | ! LOOP OVER SWEEPS
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| 95 | do nsw=1,nsweep
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| 96 | !
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| 97 | ! METROPOLIS UPDATE
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| 98 | call metropolis(eol,acz,muca_weight)
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| 99 |
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| 100 | muold = int(min(xmax,max(xmin,eol/ebin+sign(0.5d0,eol))))
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| 101 | ihist(muold) = ihist(muold) + 1
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[38d77eb] | 102 | write (logString, *) nsw, eol, acz
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[e40e335] | 103 | !
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| 104 | ! ITERATE MULTICANONICAL WEIGHTS EVERY NUP SWEEPS
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| 105 | if(mod(nsw,nup).eq.0) then
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| 106 | xhist(kmax) = xhist(kmax) + ihist(kmax)
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| 107 | xhist(kmax-1) = xhist(kmax-1) + ihist(kmax-1)
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| 108 | rewind 11
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| 109 | do i=kmax-2,kmin,-1
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| 110 | xhist(i) = xhist(i) + ihist(i)
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| 111 | if((ihist(i).gt.1).and.(ihist(i+1).gt.1)) then
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| 112 | g0 = float(ihist(i+1))*float(ihist(i))
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| 113 | g0 = g0/float(ihist(i)+ihist(i+1))
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| 114 | g1(i) = g1(i) + g0
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| 115 | g0 = g0/g1(i)
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| 116 | bi_1 = log(float(ihist(i+1)))
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| 117 | bi = log(float(ihist(i)))
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| 118 | b(i) = b(i) + g0*(bi_1 - bi)/ebin
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| 119 | else
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| 120 | if(xhist(i).lt.2.0) then
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| 121 | b(i) = max(0.0d0,b(i+1))
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| 122 | end if
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| 123 | end if
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| 124 | end do
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| 125 | b(kmax) = b(kmax-2)
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| 126 | b(kmax-1) = b(kmax-2)
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| 127 | alpha(kmax) = 0
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| 128 | ent(kmax) = (beta+b(kmax))*float(kmax)*ebin + alpha(kmax)
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| 129 | write(11,'(i5,5f15.4)') kmax,xhist(kmax),g1(kmax),
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| 130 | & b(kmax),alpha(kmax),ent(kmax)
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| 131 | ihist(kmax) = 0
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| 132 | do i=kmax-1,kmin,-1
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| 133 | ihist(i) = 0
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| 134 | alpha(i) = alpha(i+1) + (b(i+1) - b(i))*(i+0.5d0)*ebin
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| 135 | ent(i) = (beta+b(i))*float(i)*ebin + alpha(i)
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| 136 | write(11,'(i5,5f15.4)') i,xhist(i),g1(i),b(i),alpha(i),ent(i)
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| 137 | end do
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| 138 | end if
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| 139 | !
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| 140 | end do
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| 141 | ! END OF SIMULATION
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| 142 |
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| 143 | ! FINAL OUTPUT:
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| 144 | acz = acz/dble(nsw*nvr)
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[38d77eb] | 145 | write (logString, *) 'last energy',eol
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| 146 | write (logString, *) 'aczeptance rate:',acz
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[e40e335] | 147 | !
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| 148 | ! OUTPUT OF FINAL HISTOGRAM
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| 149 | !
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[38d77eb] | 150 | write (logString, *) 'Histogram:'
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[e40e335] | 151 | do i=kmin,kmax
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| 152 | if(xhist(i).gt.0.0d0) then
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[38d77eb] | 153 | write (logString, *) i,xhist(i)
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[e40e335] | 154 | end if
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| 155 | end do
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| 156 | !
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| 157 | ! WRITE DOWN MULTICANONICAL PARAMETER
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| 158 | alpha(kmax)=0.0d0
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| 159 | b(kmax) = b(kmax)+beta
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| 160 | do i= kmax-1,kmin,-1
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| 161 | b(i) = b(i) + beta
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| 162 | alpha(i) = alpha(i+1) + (b(i+1) - b(i))*(i+0.5d0)*ebin
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| 163 | end do
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| 164 | rewind 12
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| 165 | do i=kmin,kmax
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| 166 | write(12,*) i,b(i),alpha(i)
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| 167 | end do
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| 168 |
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| 169 | close(11)
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| 170 | close(12)
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| 171 | !
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| 172 | ! =====================
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| 173 | !
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| 174 | return
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| 175 | end
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| 176 |
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| 177 | !**********************************************************************
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| 178 |
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| 179 | real*8 function muca_weight(x)
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| 180 |
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| 181 | implicit real*8 (a-h,o-z)
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| 182 | implicit integer*8 (i-n)
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| 183 |
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| 184 | parameter(kmin=-12,kmax=20,ebin=1.0d0)
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| 185 |
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| 186 | common/muca/b(kmin:kmax),alpha(kmin:kmax),beta
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| 187 |
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| 188 | xmin = kmin
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| 189 | xmax = kmax
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| 190 | muold = int(min(xmax,max(xmin,x/ebin+sign(0.5d0,x))))
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| 191 | muca_weight = (beta+b(muold))*x + alpha(muold)
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| 192 |
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| 193 | return
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| 194 |
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| 195 | end
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[38d77eb] | 196 |
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