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!! Calculates Long Range forces Lennard-Jones interactions. |
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!! @author Charles F. Vardeman II |
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!! @author Matthew Meineke |
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!! @version $Id: LJ.F90,v 1.3 2004-10-21 20:15:25 gezelter Exp $, $Date: 2004-10-21 20:15:25 $, $Name: not supported by cvs2svn $, $Revision: 1.3 $ |
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|
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module lj |
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use atype_module |
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use switcheroo |
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use vector_class |
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use simulation |
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use status |
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#ifdef IS_MPI |
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use mpiSimulation |
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#endif |
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use force_globals |
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|
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implicit none |
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PRIVATE |
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|
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integer, parameter :: DP = selected_real_kind(15) |
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|
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type, private :: LjType |
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integer :: ident |
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real(kind=dp) :: sigma |
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real(kind=dp) :: epsilon |
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end type LjType |
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|
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type(LjType), dimension(:), allocatable :: ParameterMap |
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|
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logical, save :: haveMixingMap = .false. |
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|
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type :: MixParameters |
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real(kind=DP) :: sigma |
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real(kind=DP) :: epsilon |
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real(kind=dp) :: sigma6 |
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real(kind=dp) :: tp6 |
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real(kind=dp) :: tp12 |
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real(kind=dp) :: delta |
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end type MixParameters |
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|
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type(MixParameters), dimension(:,:), allocatable :: MixingMap |
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|
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real(kind=DP), save :: LJ_rcut |
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logical, save :: have_rcut = .false. |
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logical, save :: LJ_do_shift = .false. |
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logical, save :: useGeometricDistanceMixing = .false. |
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|
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!! Public methods and data |
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|
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public :: setCutoffLJ |
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public :: useGeometricMixing |
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public :: do_lj_pair |
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public :: newLJtype |
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|
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contains |
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|
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subroutine newLJtype(ident, sigma, epsilon, status) |
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integer,intent(in) :: ident |
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real(kind=dp),intent(in) :: sigma |
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real(kind=dp),intent(in) :: epsilon |
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integer,intent(out) :: status |
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integer :: nAtypes |
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|
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status = 0 |
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|
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!! Be simple-minded and assume that we need a ParameterMap that |
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!! is the same size as the total number of atom types |
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|
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if (.not.allocated(ParameterMap)) then |
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|
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nAtypes = getSize(atypes) |
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|
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if (nAtypes == 0) then |
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status = -1 |
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return |
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end if |
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|
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if (.not. allocated(ParameterMap)) then |
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allocate(ParameterMap(nAtypes)) |
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endif |
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|
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end if |
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|
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if (ident .gt. size(ParameterMap)) then |
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status = -1 |
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return |
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endif |
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|
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! set the values for ParameterMap for this atom type: |
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|
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ParameterMap(ident)%ident = ident |
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ParameterMap(ident)%epsilon = epsilon |
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ParameterMap(ident)%sigma = sigma |
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|
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end subroutine newLJtype |
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|
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subroutine setCutoffLJ(rcut, do_shift, status) |
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logical, intent(in):: do_shift |
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integer :: status, myStatus |
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real(kind=dp) :: rcut |
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|
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#define __FORTRAN90 |
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#include "UseTheForce/fSwitchingFunction.h" |
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|
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status = 0 |
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|
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LJ_rcut = rcut |
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LJ_do_shift = do_shift |
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call set_switch(LJ_SWITCH, rcut, rcut) |
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have_rcut = .true. |
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|
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return |
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end subroutine setCutoffLJ |
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|
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subroutine useGeometricMixing() |
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useGeometricDistanceMixing = .true. |
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haveMixingMap = .false. |
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return |
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end subroutine useGeometricMixing |
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|
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subroutine createMixingMap(status) |
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integer :: nAtypes |
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integer :: status |
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integer :: i |
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integer :: j |
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real ( kind = dp ) :: Sigma_i, Sigma_j |
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real ( kind = dp ) :: Epsilon_i, Epsilon_j |
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real ( kind = dp ) :: rcut6 |
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|
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status = 0 |
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|
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nAtypes = size(ParameterMap) |
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|
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if (nAtypes == 0) then |
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status = -1 |
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return |
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end if |
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|
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if (.not.have_rcut) then |
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status = -1 |
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return |
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endif |
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|
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if (.not. allocated(MixingMap)) then |
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allocate(MixingMap(nAtypes, nAtypes)) |
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endif |
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|
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rcut6 = LJ_rcut**6 |
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|
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! This loops through all atypes, even those that don't support LJ forces. |
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do i = 1, nAtypes |
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|
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Epsilon_i = ParameterMap(i)%epsilon |
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Sigma_i = ParameterMap(i)%sigma |
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|
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! do self mixing rule |
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MixingMap(i,i)%sigma = Sigma_i |
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MixingMap(i,i)%sigma6 = Sigma_i ** 6 |
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MixingMap(i,i)%tp6 = (MixingMap(i,i)%sigma6)/rcut6 |
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MixingMap(i,i)%tp12 = (MixingMap(i,i)%tp6) ** 2 |
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MixingMap(i,i)%epsilon = Epsilon_i |
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MixingMap(i,i)%delta = -4.0_DP * MixingMap(i,i)%epsilon * & |
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(MixingMap(i,i)%tp12 - MixingMap(i,i)%tp6) |
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|
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do j = i + 1, nAtypes |
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|
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Epsilon_j = ParameterMap(j)%epsilon |
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Sigma_j = ParameterMap(j)%sigma |
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|
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! only the distance parameter uses different mixing policies |
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if (useGeometricDistanceMixing) then |
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! only for OPLS as far as we can tell |
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MixingMap(i,j)%sigma = dsqrt(Sigma_i * Sigma_j) |
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else |
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! everyone else |
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MixingMap(i,j)%sigma = 0.5_dp * (Sigma_i + Sigma_j) |
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endif |
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|
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! energy parameter is always geometric mean: |
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MixingMap(i,j)%epsilon = dsqrt(Epsilon_i * Epsilon_j) |
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|
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MixingMap(i,j)%sigma6 = (MixingMap(i,j)%sigma)**6 |
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MixingMap(i,j)%tp6 = MixingMap(i,j)%sigma6/rcut6 |
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MixingMap(i,j)%tp12 = (MixingMap(i,j)%tp6) ** 2 |
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|
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MixingMap(i,j)%delta = -4.0_DP * MixingMap(i,j)%epsilon * & |
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(MixingMap(i,j)%tp12 - MixingMap(i,j)%tp6) |
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|
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MixingMap(j,i)%sigma = MixingMap(i,j)%sigma |
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MixingMap(j,i)%sigma6 = MixingMap(i,j)%sigma6 |
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MixingMap(j,i)%tp6 = MixingMap(i,j)%tp6 |
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MixingMap(j,i)%tp12 = MixingMap(i,j)%tp12 |
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MixingMap(j,i)%epsilon = MixingMap(i,j)%epsilon |
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MixingMap(j,i)%delta = MixingMap(i,j)%delta |
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|
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end do |
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end do |
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|
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end subroutine createMixingMap |
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|
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subroutine do_lj_pair(atom1, atom2, d, rij, r2, sw, vpair, fpair, & |
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pot, f, do_pot) |
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|
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integer, intent(in) :: atom1, atom2 |
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real( kind = dp ), intent(in) :: rij, r2 |
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real( kind = dp ) :: pot, sw, vpair |
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real( kind = dp ), dimension(3,nLocal) :: f |
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real( kind = dp ), intent(in), dimension(3) :: d |
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real( kind = dp ), intent(inout), dimension(3) :: fpair |
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logical, intent(in) :: do_pot |
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|
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! local Variables |
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real( kind = dp ) :: drdx, drdy, drdz |
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real( kind = dp ) :: fx, fy, fz |
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real( kind = dp ) :: pot_temp, dudr |
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real( kind = dp ) :: sigma6 |
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real( kind = dp ) :: epsilon |
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real( kind = dp ) :: r6 |
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real( kind = dp ) :: t6 |
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real( kind = dp ) :: t12 |
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real( kind = dp ) :: delta |
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integer :: id1, id2, localError |
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|
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if (.not.haveMixingMap) then |
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localError = 0 |
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call createMixingMap(localError) |
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if ( localError .ne. 0 ) then |
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call handleError("LJ", "MixingMap creation failed!") |
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return |
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end if |
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endif |
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|
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! Look up the correct parameters in the mixing matrix |
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#ifdef IS_MPI |
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sigma6 = MixingMap(atid_Row(atom1),atid_Col(atom2))%sigma6 |
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epsilon = MixingMap(atid_Row(atom1),atid_Col(atom2))%epsilon |
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delta = MixingMap(atid_Row(atom1),atid_Col(atom2))%delta |
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#else |
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sigma6 = MixingMap(atid(atom1),atid(atom2))%sigma6 |
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epsilon = MixingMap(atid(atom1),atid(atom2))%epsilon |
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delta = MixingMap(atid(atom1),atid(atom2))%delta |
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#endif |
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|
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r6 = r2 * r2 * r2 |
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|
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t6 = sigma6/ r6 |
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t12 = t6 * t6 |
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|
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pot_temp = 4.0E0_DP * epsilon * (t12 - t6) |
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if (LJ_do_shift) then |
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pot_temp = pot_temp + delta |
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endif |
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|
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vpair = vpair + pot_temp |
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|
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dudr = sw * 24.0E0_DP * epsilon * (t6 - 2.0E0_DP*t12) / rij |
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|
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drdx = d(1) / rij |
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drdy = d(2) / rij |
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drdz = d(3) / rij |
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|
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fx = dudr * drdx |
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fy = dudr * drdy |
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fz = dudr * drdz |
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|
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|
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#ifdef IS_MPI |
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if (do_pot) then |
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pot_Row(atom1) = pot_Row(atom1) + sw*pot_temp*0.5 |
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pot_Col(atom2) = pot_Col(atom2) + sw*pot_temp*0.5 |
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endif |
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|
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f_Row(1,atom1) = f_Row(1,atom1) + fx |
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f_Row(2,atom1) = f_Row(2,atom1) + fy |
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f_Row(3,atom1) = f_Row(3,atom1) + fz |
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|
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f_Col(1,atom2) = f_Col(1,atom2) - fx |
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f_Col(2,atom2) = f_Col(2,atom2) - fy |
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f_Col(3,atom2) = f_Col(3,atom2) - fz |
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|
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#else |
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if (do_pot) pot = pot + sw*pot_temp |
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|
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f(1,atom1) = f(1,atom1) + fx |
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f(2,atom1) = f(2,atom1) + fy |
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f(3,atom1) = f(3,atom1) + fz |
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|
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f(1,atom2) = f(1,atom2) - fx |
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f(2,atom2) = f(2,atom2) - fy |
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f(3,atom2) = f(3,atom2) - fz |
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#endif |
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|
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#ifdef IS_MPI |
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id1 = AtomRowToGlobal(atom1) |
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id2 = AtomColToGlobal(atom2) |
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#else |
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id1 = atom1 |
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id2 = atom2 |
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#endif |
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|
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if (molMembershipList(id1) .ne. molMembershipList(id2)) then |
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|
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fpair(1) = fpair(1) + fx |
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fpair(2) = fpair(2) + fy |
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fpair(3) = fpair(3) + fz |
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|
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endif |
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|
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return |
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|
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end subroutine do_lj_pair |
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|
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|
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!! Calculates the mixing for sigma or epslon |
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|
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end module lj |
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|
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subroutine newLJtype(ident, sigma, epsilon, status) |
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use lj, ONLY : module_newLJtype => newLJtype |
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integer, parameter :: DP = selected_real_kind(15) |
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integer,intent(inout) :: ident |
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real(kind=dp),intent(inout) :: sigma |
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real(kind=dp),intent(inout) :: epsilon |
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integer,intent(inout) :: status |
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|
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call module_newLJtype(ident, sigma, epsilon, status) |
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|
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end subroutine newLJtype |
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|
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subroutine useGeometricMixing() |
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use lj, ONLY: module_useGeometricMixing => useGeometricMixing |
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|
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call module_useGeometricMixing() |
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return |
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end subroutine useGeometricMixing |
