exchange_operator.F90

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!! Copyright (C) 2002-2018 M. Marques, A. Castro, A. Rubio, G. Bertsch, N. Tancogne-Dejean
!!
!! This program is free software; you can redistribute it and/or modify
!! it under the terms of the GNU General Public License as published by
!! the Free Software Foundation; either version 2, or (at your option)
!! any later version.
!!
!! This program is distributed in the hope that it will be useful,
!! but WITHOUT ANY WARRANTY; without even the implied warranty of
!! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
!! GNU General Public License for more details.
!!
!! You should have received a copy of the GNU General Public License
!! along with this program; if not, write to the Free Software
!! Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
!! 02110-1301, USA.
!!
 
#include "global.h"
 
module exchange_operator_oct_m
  use batch_oct_m
  use batch_ops_oct_m
  use comm_oct_m
  use debug_oct_m
  use derivatives_oct_m
  use electron_space_oct_m
  use fourier_space_oct_m
  use global_oct_m
  use grid_oct_m
  use kpoints_oct_m
  use lalg_adv_oct_m
  use lalg_basic_oct_m
  use math_oct_m
  use mesh_oct_m
  use mesh_function_oct_m
  use mesh_batch_oct_m
  use messages_oct_m
  use mpi_oct_m
  use multicomm_oct_m
  use namespace_oct_m
  use par_vec_oct_m
  use parser_oct_m
  use phase_oct_m
  use poisson_oct_m
  use profiling_oct_m
  use ring_pattern_oct_m
  use singularity_oct_m
  use space_oct_m
  use states_abst_oct_m
  use states_elec_oct_m
  use states_elec_dim_oct_m
  use states_elec_parallel_oct_m
  use stencil_oct_m
  use symmetries_oct_m
  use states_elec_all_to_all_communications_oct_m
  use unit_oct_m
  use unit_system_oct_m
  use wfs_elec_oct_m
 
  implicit none
 
  private
  public ::                          &
    exchange_operator_t,             &
    exchange_operator_init,          &
    exchange_operator_reinit,        &
    exchange_operator_end,           &
    dexchange_operator_single,       &
    zexchange_operator_single,       &
    dexchange_operator_apply,        &
    zexchange_operator_apply,        &
    dexchange_operator_hartree_apply,&
    zexchange_operator_hartree_apply,&
    exchange_operator_rdmft_occ_apply,&
    dexchange_operator_compute_potentials, &
    zexchange_operator_compute_potentials, &
    dexchange_operator_commute_r, &
    zexchange_operator_commute_r, &
    dexchange_operator_ace, &
    zexchange_operator_ace
 
 
  type ace_t
    integer :: nst
    real(real64), allocatable :: dchi(:,:,:,:)
    complex(real64), allocatable :: zchi(:,:,:,:)
  end type ace_t
 
  type exchange_operator_t
    type(states_elec_t), public, pointer :: st => null()
    real(real64) :: cam_omega = m_zero
    real(real64) :: cam_alpha = m_zero
    real(real64) :: cam_beta = m_zero
 
    type(poisson_t) :: psolver
 
    type(singularity_t) :: singul
 
    logical       :: useACE = .false.
    type(ACE_t)   :: ace
  end type exchange_operator_t
 
  type(fourier_space_op_t) :: coulb
  !                                    Saved as we avoid then to recompute it,
  !                                    for instance in the case of CAM functionals in isolated systems
 
  real(real64), parameter, private :: TOL_EXX_WEIGHT = 1.0e-3_real64 
 
contains
 
  subroutine exchange_operator_init(this, namespace, space, st, der, mc, stencil, kpoints, omega, alpha, beta)
    type(exchange_operator_t), intent(inout) :: this
    type(namespace_t),         intent(in)    :: namespace
    class(space_t),            intent(in)    :: space
    type(states_elec_t),       intent(in)    :: st
    type(derivatives_t),       intent(in)    :: der
    type(multicomm_t),         intent(in)    :: mc
    type(stencil_t),           intent(in)    :: stencil
    type(kpoints_t),           intent(in)    :: kpoints
    real(real64),              intent(in)    :: alpha, beta, omega
 
    push_sub(exchange_operator_init)
 
    this%cam_omega = omega
    this%cam_alpha = alpha
    this%cam_beta  = beta
 
    !%Variable AdaptivelyCompressedExchange
    !%Type logical
    !%Default false
    !%Section Hamiltonian
    !%Description
    !% If set to yes, Octopus will use the adaptively compressed exchange
    !% operator (ACE) for HF and hybrid calculations, as defined in
    !%  Lin, J. Chem. Theory Comput. 2016, 12, 2242.
    !%
    !% This is currenly ignored for TheoryLevel = rdmft
    !%End
    call parse_variable(namespace, 'AdaptivelyCompressedExchange', .true., this%useACE)
 
    call singularity_init(this%singul, namespace, space, st, kpoints)
    if (states_are_real(st)) then
      call poisson_init(this%psolver, namespace, space, der, mc, stencil, st%qtot, &
        force_serial = .true., verbose = .false.)
    else
      call poisson_init(this%psolver, namespace, space, der, mc, stencil, st%qtot, &
        force_serial = .true., verbose = .false., force_cmplx = .true.)
    end if
 
    pop_sub(exchange_operator_init)
  end subroutine exchange_operator_init
 
  subroutine exchange_operator_reinit(this, omega, alpha, beta, st)
    type(exchange_operator_t),           intent(inout) :: this
    real(real64),                        intent(in)    :: omega, alpha, beta
    type(states_elec_t), target, optional, intent(in)  :: st
 
    push_sub(exchange_operator_reinit)
 
    if (present(st)) then
      this%st => st
    end if
 
    this%cam_omega = omega
    this%cam_alpha = alpha
    this%cam_beta  = beta
 
    pop_sub(exchange_operator_reinit)
  end subroutine exchange_operator_reinit
 
  subroutine exchange_operator_end(this)
    type(exchange_operator_t), intent(inout) :: this
 
    push_sub(exchange_operator_end)
 
    if (associated(this%st) .and. .not. this%useACE) then
      call states_elec_parallel_remote_access_stop(this%st)
      call states_elec_end(this%st)
      safe_deallocate_p(this%st)
    end if
    nullify(this%st)
 
    this%ace%nst = 0
    safe_deallocate_a(this%ace%dchi)
    safe_deallocate_a(this%ace%zchi)
 
    call singularity_end(this%singul)
    call fourier_space_op_end(coulb)
    call poisson_end(this%psolver)
 
    pop_sub(exchange_operator_end)
  end subroutine exchange_operator_end
 
  subroutine exchange_operator_rdmft_occ_apply(this, mesh, hpsib)
    type(exchange_operator_t), intent(in) :: this
    type(mesh_t),              intent(in) :: mesh
    class(wfs_elec_t),      intent(inout) :: hpsib
 
    push_sub(exchange_operator_rdmft_occ_apply)
 
    ! multiply linear terms in hamiltonian with occupation number
    ! nonlinear occupation number dependency occurs only in the exchange, which is treated there
    call batch_scal(mesh%np, this%st%occ(:, hpsib%ik), hpsib)
 
    pop_sub(exchange_operator_rdmft_occ_apply)
  end subroutine exchange_operator_rdmft_occ_apply
 
 
#include "undef.F90"
#include "real.F90"
#include "exchange_operator_inc.F90"
 
#include "undef.F90"
#include "complex.F90"
#include "exchange_operator_inc.F90"
 
end module exchange_operator_oct_m
 
!! Local Variables:
!! mode: f90
!! coding: utf-8
!! End: