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!! Calculates Long Range forces Lennard-Jones interactions. |
| 2 |
!! Corresponds to the force field defined in lj_FF.cpp |
| 3 |
!! @author Charles F. Vardeman II |
| 4 |
!! @author Matthew Meineke |
| 5 |
!! @version $Id: LJ.F90,v 1.2 2004-10-21 15:25:30 chuckv Exp $, $Date: 2004-10-21 15:25:30 $, $Name: not supported by cvs2svn $, $Revision: 1.2 $ |
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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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#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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#define __FORTRAN90 |
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#include "UseTheForce/fForceField.h" |
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|
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integer, save :: LJ_Mixing_Policy |
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real(kind=DP), save :: LJ_rcut |
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logical, save :: havePolicy = .false. |
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logical, save :: haveCut = .false. |
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logical, save :: LJ_do_shift = .false. |
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|
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!! Logical has lj force field module been initialized? |
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|
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logical, save :: LJ_FF_initialized = .false. |
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|
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!! Public methods and data |
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public :: init_LJ_FF |
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public :: setCutoffLJ |
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public :: do_lj_pair |
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public :: newLJtype |
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|
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!! structure for lj type parameters |
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type, private :: ljType |
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integer :: lj_ident |
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real(kind=dp) :: lj_sigma |
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real(kind=dp) :: lj_epsilon |
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end type ljType |
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|
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!! List of lj type parameters |
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type, private :: ljTypeList |
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integer :: n_lj_types = 0 |
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integer :: currentAddition = 0 |
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type(ljType), pointer :: ljParams(:) => null() |
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end type ljTypeList |
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|
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!! The list of lj Parameters |
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type (ljTypeList), save :: ljParameterList |
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|
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|
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type :: lj_mixed_params |
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!! Lennard-Jones epsilon |
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real ( kind = dp ) :: epsilon = 0.0_dp |
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!! Lennard-Jones Sigma |
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real ( kind = dp ) :: sigma = 0.0_dp |
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!! Lennard-Jones Sigma to sixth |
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real ( kind = dp ) :: sigma6 = 0.0_dp |
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!! |
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real ( kind = dp ) :: tp6 |
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real ( kind = dp ) :: tp12 |
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real ( kind = dp ) :: delta = 0.0_dp |
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end type lj_mixed_params |
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|
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type (lj_mixed_params), dimension(:,:), pointer :: ljMixed |
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|
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|
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|
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contains |
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|
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subroutine newLJtype(ident,lj_sigma,lj_epsilon,status) |
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integer,intent(in) :: ident |
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real(kind=dp),intent(in) :: lj_sigma |
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real(kind=dp),intent(in) :: lj_epsilon |
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integer,intent(out) :: status |
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|
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integer,pointer :: Matchlist(:) => null() |
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integer :: current |
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integer :: nAtypes |
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status = 0 |
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|
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!! Assume that atypes has already been set and get the total number of types in atypes |
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|
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|
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|
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! check to see if this is the first time into |
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if (.not.associated(ljParameterList%ljParams)) then |
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call getMatchingElementList(atypes, "is_lj", .true., nAtypes, MatchList) |
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ljParameterList%n_lj_types = nAtypes |
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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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allocate(ljParameterList%ljParams(nAtypes)) |
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end if |
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|
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ljParameterList%currentAddition = ljParameterList%currentAddition + 1 |
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current = ljParameterList%currentAddition |
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|
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! set the values for ljParameterList |
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ljParameterList%ljParams(current)%lj_ident = ident |
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ljParameterList%ljParams(current)%lj_epsilon = lj_epsilon |
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ljParameterList%ljParams(current)%lj_sigma = lj_sigma |
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|
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end subroutine newLJtype |
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|
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subroutine init_LJ_FF(mix_Policy, status) |
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integer, intent(in) :: mix_Policy |
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integer, intent(out) :: status |
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integer :: myStatus |
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|
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if (mix_Policy == LB_MIXING_RULE) then |
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LJ_Mixing_Policy = LB_MIXING_RULE |
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else |
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if (mix_Policy == EXPLICIT_MIXING_RULE) then |
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LJ_Mixing_Policy = EXPLICIT_MIXING_RULE |
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else |
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write(*,*) 'Unknown Mixing Policy!' |
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status = -1 |
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return |
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endif |
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endif |
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|
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havePolicy = .true. |
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|
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if (haveCut) then |
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status = 0 |
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call createMixingList(myStatus) |
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if (myStatus /= 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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LJ_FF_initialized = .true. |
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end if |
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|
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end subroutine init_LJ_FF |
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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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haveCut = .true. |
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|
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if (havePolicy) then |
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status = 0 |
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call createMixingList(myStatus) |
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if (myStatus /= 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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LJ_FF_initialized = .true. |
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end if |
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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 createMixingList(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 ) :: mySigma_i,mySigma_j |
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real ( kind = dp ) :: myEpsilon_i,myEpsilon_j |
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real ( kind = dp ) :: rcut6 |
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logical :: I_isLJ, J_isLJ |
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status = 0 |
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|
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! we only allocate this array to the number of lj_atypes |
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nAtypes = size(ljParameterList%ljParams) |
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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. associated(ljMixed)) then |
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allocate(ljMixed(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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myEpsilon_i = ljParameterList%ljParams(i)%lj_epsilon |
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mySigma_i = ljParameterList%ljParams(i)%lj_sigma |
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|
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! do self mixing rule |
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ljMixed(i,i)%sigma = mySigma_i |
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|
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ljMixed(i,i)%sigma6 = (ljMixed(i,i)%sigma) ** 6 |
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|
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ljMixed(i,i)%tp6 = (ljMixed(i,i)%sigma6)/rcut6 |
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|
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ljMixed(i,i)%tp12 = (ljMixed(i,i)%tp6) ** 2 |
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|
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|
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ljMixed(i,i)%epsilon = myEpsilon_i |
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|
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ljMixed(i,i)%delta = -4.0_DP * ljMixed(i,i)%epsilon * & |
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(ljMixed(i,i)%tp12 - ljMixed(i,i)%tp6) |
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|
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do j = i + 1, nAtypes |
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|
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myEpsilon_j = ljParameterList%ljParams(j)%lj_epsilon |
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mySigma_j = ljParameterList%ljParams(j)%lj_sigma |
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|
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|
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ljMixed(i,j)%sigma = & |
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calcLJMix("sigma",mySigma_i, & |
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mySigma_j) |
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|
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ljMixed(i,j)%sigma6 = & |
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(ljMixed(i,j)%sigma)**6 |
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|
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|
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ljMixed(i,j)%tp6 = ljMixed(i,j)%sigma6/rcut6 |
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|
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ljMixed(i,j)%tp12 = (ljMixed(i,j)%tp6) ** 2 |
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|
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|
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ljMixed(i,j)%epsilon = & |
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calcLJMix("epsilon",myEpsilon_i, & |
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myEpsilon_j) |
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|
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ljMixed(i,j)%delta = -4.0_DP * ljMixed(i,j)%epsilon * & |
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(ljMixed(i,j)%tp12 - ljMixed(i,j)%tp6) |
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|
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|
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ljMixed(j,i)%sigma = ljMixed(i,j)%sigma |
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ljMixed(j,i)%sigma6 = ljMixed(i,j)%sigma6 |
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ljMixed(j,i)%tp6 = ljMixed(i,j)%tp6 |
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ljMixed(j,i)%tp12 = ljMixed(i,j)%tp12 |
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ljMixed(j,i)%epsilon = ljMixed(i,j)%epsilon |
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ljMixed(j,i)%delta = ljMixed(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 createMixingList |
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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 |
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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 = ljMixed(atid_Row(atom1),atid_Col(atom2))%sigma6 |
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epsilon = ljMixed(atid_Row(atom1),atid_Col(atom2))%epsilon |
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delta = ljMixed(atid_Row(atom1),atid_Col(atom2))%delta |
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#else |
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sigma6 = ljMixed(atid(atom1),atid(atom2))%sigma6 |
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epsilon = ljMixed(atid(atom1),atid(atom2))%epsilon |
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delta = ljMixed(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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|
| 365 |
function calcLJMix(thisParam,param1,param2,status) result(myMixParam) |
| 366 |
character(len=*) :: thisParam |
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real(kind = dp) :: param1 |
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real(kind = dp) :: param2 |
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real(kind = dp ) :: myMixParam |
| 370 |
|
| 371 |
integer, optional :: status |
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|
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myMixParam = 0.0_dp |
| 374 |
|
| 375 |
if (present(status)) status = 0 |
| 376 |
select case (LJ_Mixing_Policy) |
| 377 |
case (1) |
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select case (thisParam) |
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case ("sigma") |
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myMixParam = 0.5_dp * (param1 + param2) |
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case ("epsilon") |
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myMixParam = sqrt(param1 * param2) |
| 383 |
case default |
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status = -1 |
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end select |
| 386 |
case default |
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status = -1 |
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end select |
| 389 |
end function calcLJMix |
| 390 |
|
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end module lj |
| 392 |
|
| 393 |
subroutine newLJtype(ident,lj_sigma,lj_epsilon,status) |
| 394 |
use lj, ONLY : module_newLJtype => newLJtype |
| 395 |
integer, parameter :: DP = selected_real_kind(15) |
| 396 |
integer,intent(inout) :: ident |
| 397 |
real(kind=dp),intent(inout) :: lj_sigma |
| 398 |
real(kind=dp),intent(inout) :: lj_epsilon |
| 399 |
integer,intent(inout) :: status |
| 400 |
|
| 401 |
call module_newLJtype(ident,lj_sigma,lj_epsilon,status) |
| 402 |
|
| 403 |
end subroutine newLJtype |
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|
