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!--------------------------------------------------------------------------------------------------!
! CP2K: A general program to perform molecular dynamics simulations !
! Copyright (C) 2000 - 2018 CP2K developers group !
!--------------------------------------------------------------------------------------------------!
! **************************************************************************************************
!> \par History
!> EAM potential
!> \author CJM, I-Feng W. Kuo, Teodoro Laino
! **************************************************************************************************
MODULE manybody_eam
USE bibliography, ONLY: Foiles1986,&
cite_reference
USE cell_types, ONLY: cell_type
USE cp_para_types, ONLY: cp_para_env_type
USE fist_neighbor_list_types, ONLY: fist_neighbor_type,&
neighbor_kind_pairs_type
USE fist_nonbond_env_types, ONLY: eam_type,&
fist_nonbond_env_get,&
fist_nonbond_env_set,&
fist_nonbond_env_type,&
pos_type
USE kinds, ONLY: dp
USE mathlib, ONLY: matvec_3x3
USE message_passing, ONLY: mp_sum
USE pair_potential_types, ONLY: ea_type,&
eam_pot_type,&
pair_potential_pp_type
USE particle_types, ONLY: particle_type
#include "./base/base_uses.f90"
IMPLICIT NONE
PRIVATE
PUBLIC :: get_force_eam, density_nonbond
CHARACTER(len=*), PARAMETER, PRIVATE :: moduleN = 'manybody_eam'
CONTAINS
! **************************************************************************************************
!> \brief ...
!> \param fist_nonbond_env ...
!> \param particle_set ...
!> \param cell ...
!> \param para_env ...
!> \author CJM
! **************************************************************************************************
SUBROUTINE density_nonbond(fist_nonbond_env, particle_set, cell, para_env)
TYPE(fist_nonbond_env_type), POINTER :: fist_nonbond_env
TYPE(particle_type), DIMENSION(:), INTENT(INOUT) :: particle_set
TYPE(cell_type), POINTER :: cell
TYPE(cp_para_env_type), POINTER :: para_env
CHARACTER(LEN=*), PARAMETER :: routineN = 'density_nonbond', &
routineP = moduleN//':'//routineN
INTEGER :: atom_a, atom_b, handle, i, i_a, i_b, &
iend, igrp, ikind, ilist, ipair, &
iparticle, istart, jkind, kind_a, &
kind_b, nkinds, nparticle
INTEGER, ALLOCATABLE, DIMENSION(:, :) :: eam_kinds_index
LOGICAL :: do_eam
REAL(KIND=dp) :: fac, rab2, rab2_max
REAL(KIND=dp), DIMENSION(3) :: cell_v, rab
REAL(KIND=dp), DIMENSION(:), POINTER :: rho
TYPE(eam_pot_type), POINTER :: eam_a, eam_b
TYPE(eam_type), DIMENSION(:), POINTER :: eam_data
TYPE(fist_neighbor_type), POINTER :: nonbonded
TYPE(neighbor_kind_pairs_type), POINTER :: neighbor_kind_pair
TYPE(pair_potential_pp_type), POINTER :: potparm
TYPE(pos_type), DIMENSION(:), POINTER :: r_last_update, r_last_update_pbc
CALL timeset(routineN, handle)
do_eam = .FALSE.
CALL fist_nonbond_env_get(fist_nonbond_env, nonbonded=nonbonded, &
potparm=potparm, r_last_update=r_last_update, &
r_last_update_pbc=r_last_update_pbc, eam_data=eam_data)
nkinds = SIZE(potparm%pot, 1)
ALLOCATE (eam_kinds_index(nkinds, nkinds))
eam_kinds_index = -1
DO ikind = 1, nkinds
DO jkind = ikind, nkinds
DO i = 1, SIZE(potparm%pot(ikind, jkind)%pot%type)
IF (potparm%pot(ikind, jkind)%pot%type(i) == ea_type) THEN
! At the moment we allow only 1 EAM per each kinds pair..
CPASSERT(eam_kinds_index(ikind, jkind) == -1)
CPASSERT(eam_kinds_index(jkind, ikind) == -1)
eam_kinds_index(ikind, jkind) = i
eam_kinds_index(jkind, ikind) = i
do_eam = .TRUE.
END IF
END DO
END DO
END DO
nparticle = SIZE(particle_set)
IF (do_eam) THEN
IF (.NOT. ASSOCIATED(eam_data)) THEN
ALLOCATE (eam_data(nparticle))
CALL fist_nonbond_env_set(fist_nonbond_env, eam_data=eam_data)
ENDIF
DO i = 1, nparticle
eam_data(i)%rho = 0.0_dp
eam_data(i)%f_embed = 0.0_dp
ENDDO
ENDIF
! Only if EAM potential are present
IF (do_eam) THEN
! Add citation
CALL cite_reference(Foiles1986)
NULLIFY (eam_a, eam_b)
ALLOCATE (rho(nparticle))
rho = 0._dp
! Starting the force loop
DO ilist = 1, nonbonded%nlists
neighbor_kind_pair => nonbonded%neighbor_kind_pairs(ilist)
IF (neighbor_kind_pair%npairs == 0) CYCLE
Kind_Group_Loop: DO igrp = 1, neighbor_kind_pair%ngrp_kind
istart = neighbor_kind_pair%grp_kind_start(igrp)
iend = neighbor_kind_pair%grp_kind_end(igrp)
ikind = neighbor_kind_pair%ij_kind(1, igrp)
jkind = neighbor_kind_pair%ij_kind(2, igrp)
i = eam_kinds_index(ikind, jkind)
IF (i == -1) CYCLE
rab2_max = potparm%pot(ikind, jkind)%pot%rcutsq
CALL matvec_3x3(cell_v, cell%hmat, REAL(neighbor_kind_pair%cell_vector, KIND=dp))
DO ipair = istart, iend
atom_a = neighbor_kind_pair%list(1, ipair)
atom_b = neighbor_kind_pair%list(2, ipair)
fac = 1.0_dp
IF (atom_a == atom_b) fac = 0.5_dp
rab = r_last_update_pbc(atom_b)%r-r_last_update_pbc(atom_a)%r
rab = rab+cell_v
rab2 = rab(1)*rab(1)+rab(2)*rab(2)+rab(3)*rab(3)
IF (rab2 <= rab2_max) THEN
kind_a = particle_set(atom_a)%atomic_kind%kind_number
kind_b = particle_set(atom_b)%atomic_kind%kind_number
i_a = eam_kinds_index(kind_a, kind_a)
i_b = eam_kinds_index(kind_b, kind_b)
eam_a => potparm%pot(kind_a, kind_a)%pot%set(i_a)%eam
eam_b => potparm%pot(kind_b, kind_b)%pot%set(i_b)%eam
CALL get_rho_eam(eam_a, eam_b, rab2, atom_a, atom_b, rho, fac)
END IF
END DO
END DO Kind_Group_Loop
END DO
CALL mp_sum(rho, para_env%group)
DO iparticle = 1, nparticle
eam_data(iparticle)%rho = rho(iparticle)
END DO
DEALLOCATE (rho)
END IF
DEALLOCATE (eam_kinds_index)
CALL timestop(handle)
END SUBROUTINE density_nonbond
! **************************************************************************************************
!> \brief ...
!> \param eam_a ...
!> \param eam_b ...
!> \param rab2 ...
!> \param atom_a ...
!> \param atom_b ...
!> \param rho ...
!> \param fac ...
!> \author CJM
! **************************************************************************************************
SUBROUTINE get_rho_eam(eam_a, eam_b, rab2, atom_a, atom_b, rho, fac)
TYPE(eam_pot_type), POINTER :: eam_a, eam_b
REAL(dp), INTENT(IN) :: rab2
INTEGER, INTENT(IN) :: atom_a, atom_b
REAL(dp), INTENT(INOUT) :: rho(:)
REAL(dp), INTENT(IN) :: fac
CHARACTER(LEN=*), PARAMETER :: routineN = 'get_rho_eam', routineP = moduleN//':'//routineN
INTEGER :: index
REAL(dp) :: qq, rab, rhoi, rhoj
rab = SQRT(rab2)
! Particle A
index = INT(rab/eam_b%drar)+1
IF (index > eam_b%npoints) THEN
index = eam_b%npoints
ELSEIF (index < 1) THEN
index = 1
ENDIF
qq = rab-eam_b%rval(index)
rhoi = eam_b%rho(index)+qq*eam_b%rhop(index)
! Particle B
index = INT(rab/eam_a%drar)+1
IF (index > eam_a%npoints) THEN
index = eam_a%npoints
ELSEIF (index < 1) THEN
index = 1
ENDIF
qq = rab-eam_a%rval(index)
rhoj = eam_a%rho(index)+qq*eam_a%rhop(index)
rho(atom_a) = rho(atom_a)+rhoi*fac
rho(atom_b) = rho(atom_b)+rhoj*fac
END SUBROUTINE get_rho_eam
! **************************************************************************************************
!> \brief ...
!> \param rab2 ...
!> \param eam_a ...
!> \param eam_b ...
!> \param eam_data ...
!> \param atom_a ...
!> \param atom_b ...
!> \param f_eam ...
!> \author CJM
! **************************************************************************************************
SUBROUTINE get_force_eam(rab2, eam_a, eam_b, eam_data, atom_a, atom_b, f_eam)
REAL(dp), INTENT(IN) :: rab2
TYPE(eam_pot_type), POINTER :: eam_a, eam_b
TYPE(eam_type), INTENT(IN) :: eam_data(:)
INTEGER, INTENT(IN) :: atom_a, atom_b
REAL(dp), INTENT(OUT) :: f_eam
CHARACTER(LEN=*), PARAMETER :: routineN = 'get_force_eam', routineP = moduleN//':'//routineN
INTEGER :: index
REAL(KIND=dp) :: denspi, denspj, fcp, qq, rab
rab = SQRT(rab2)
! Particle A
index = INT(rab/eam_a%drar)+1
IF (index > eam_a%npoints) THEN
index = eam_a%npoints
ELSEIF (index < 1) THEN
index = 1
ENDIF
qq = rab-eam_a%rval(index)
IF (index == eam_a%npoints) THEN
denspi = eam_a%rhop(index)+qq*(eam_a%rhop(index)-eam_a%rhop(index-1))/eam_a%drar
ELSE
denspi = eam_a%rhop(index)+qq*(eam_a%rhop(index+1)-eam_a%rhop(index))/eam_a%drar
END IF
! Particle B
index = INT(rab/eam_b%drar)+1
IF (index > eam_b%npoints) THEN
index = eam_b%npoints
ELSEIF (index < 1) THEN
index = 1
ENDIF
qq = rab-eam_b%rval(index)
IF (index == eam_b%npoints) THEN
denspj = eam_b%rhop(index)+qq*(eam_b%rhop(index)-eam_b%rhop(index-1))/eam_b%drar
ELSE
denspj = eam_b%rhop(index)+qq*(eam_b%rhop(index+1)-eam_b%rhop(index))/eam_b%drar
END IF
fcp = denspj*eam_data(atom_a)%f_embed+denspi*eam_data(atom_b)%f_embed
f_eam = fcp/rab
END SUBROUTINE get_force_eam
END MODULE manybody_eam
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