| 1 | ! *********************************************************************
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| 2 | ! This file contains eninteract
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| 3 | !
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| 4 | ! Copyright 2007 Frank Eisenmenger, U.H.E. Hansmann,
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| 5 | ! Jan H. Meinke, Sandipan Mohanty
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| 6 | !
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| 7 | !
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| 8 | ! Description: Calculates the interaction energy between molecules
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| 9 | ! The function assumes that all molecules are up-to-date. If in doubt
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| 10 | ! call energy first.
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| 11 | ! The energy function is based on the ECEPP/3 dataset.
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| 12 | !
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| 13 | ! TODO: Intermolecular interaction energy for FLEX and ECEPP/2
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| 14 | real*8 function eninteract()
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| 15 |
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| 16 | include 'INCL.H'
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| 17 |
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| 18 | double precision cqi, xi, yi, zi, xj, yj, zj, xij, yij, zij, rij2
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| 19 | double precision rij4, rij6, rij, sr, ep
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| 20 |
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| 21 | integer iml, jml, ires, jres, iat, ity, jat, jty
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| 22 |
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| 23 | eysmi=0.0
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| 24 | eyeli=0.0
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| 25 | eyvwi=0.0
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| 26 | eyhbi=0.0
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| 27 |
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| 28 | do iml = 1, ntlml
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| 29 | do jml = iml + 1, ntlml
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| 30 | do ires= irsml1(iml), irsml2(iml)
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| 31 | do jres= irsml1(jml), irsml2(jml)
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| 32 | do iat = iatrs1(ires), iatrs2(ires)
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| 33 | ! Atom class of current atom
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| 34 | ity=ityat(iat)
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| 35 | ! Point charge at current atom
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| 36 | cqi=conv*cgat(iat)
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| 37 | ! Cartesian coordinates of current atom
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| 38 | xi=xat(iat)
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| 39 | yi=yat(iat)
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| 40 | zi=zat(iat)
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| 41 |
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| 42 | do jat = iatrs1(jres), iatrs2(jres)
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| 43 | ! Atom type of partner
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| 44 | jty=ityat(jat)
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| 45 | ! Differences in cartesian coordinates
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| 46 | xj=xat(jat)
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| 47 | yj=yat(jat)
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| 48 | zj=zat(jat)
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| 49 |
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| 50 | xij=xat(jat)-xi
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| 51 | yij=yat(jat)-yi
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| 52 | zij=zat(jat)-zi
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| 53 | ! Cartesian distance and higher powers
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| 54 | rij2=xij*xij+yij*yij+zij*zij
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| 55 | rij4=rij2*rij2
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| 56 | rij6=rij4*rij2
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| 57 | rij=sqrt(rij2)
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| 58 | ! Are we using a distance dependent dielectric constant?
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| 59 | if(epsd) then
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| 60 | sr=slp*rij
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| 61 | ep=plt-(sr*sr+2.0*sr+2.0)*(plt-1.0)*exp(-sr)/2.0
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| 62 | else
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| 63 | ep = 1.0d0
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| 64 | end if
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| 65 | ! Coulomb interaction
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| 66 | eyeli=eyeli+cqi*cgat(jat)/(rij*ep)
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| 67 | ! If the two atoms cannot form a hydrogen bond use 6-12 Lennard-Jones potential
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| 68 | if (ihbty(ity,jty).eq.0) then
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| 69 | eyvwi=eyvwi+aij(ity,jty)/(rij6*rij6)
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| 70 | & -cij(ity,jty)/rij6
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| 71 | else
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| 72 | ! For hydrogen bonding use 10-12 Lennard-Jones potential
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| 73 | eyhbi=eyhbi+ahb(ity,jty)/(rij6*rij6)
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| 74 | & -chb(ity,jty)/(rij6*rij4)
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| 75 | endif
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| 76 | enddo
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| 77 | enddo
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| 78 | enddo
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| 79 | enddo
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| 80 | enddo
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| 81 | enddo
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| 82 |
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| 83 | eysmi = eyeli + eyvwi + eyhbi
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| 84 | eninteract = eysmi
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| 85 | return
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| 86 | end
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