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ABINIT/fock_ACE_getghc [ Functions ]

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NAME

  fock_ACE_getghc

FUNCTION

  Compute the matrix elements <G|Vx|psi> of the Fock operator in the ACE context.

COPYRIGHT

  Copyright (C) 2013-2018 ABINIT group (CMartins,FJ,MT)
  This file is distributed under the terms of the
  GNU General Public License, see ~abinit/COPYING
  or http://www.gnu.org/copyleft/gpl.txt .

INPUTS

  cwavef(2,npw*nspinor*ndat)= planewave coefficients of wavefunctions on which Fock operator is applied.
  gs_ham <type(gs_hamiltonian_type)>=all data for the Hamiltonian to be applied
  mpi_enreg= information about MPI parallelization

SIDE EFFECTS

  ghc(2,npw*ndat)= matrix elements <G|H|C> or <G|H-lambda.S|C> (if sij_opt>=0 or =-1 in getghc)
                   contains the fock exchange term for cwavef at the end.

NOTES

  The current version assumes that :
   * nspinor = 1
   * no "my_nspinor"
   * no restriction to the value of istwfk_bz (but must be tested in all case)
   * all the data for the occupied states (cgocc_bz) are the same as those for the current states (cg)

PARENTS

      getghc

CHILDREN

      dotprod_g

SOURCE

 39 #if defined HAVE_CONFIG_H
 40 #include "config.h"
 41 #endif
 42 
 43 #include "abi_common.h"
 44 
 45 subroutine fock_ACE_getghc(cwavef,ghc,gs_ham,mpi_enreg)
 46 
 47  use defs_basis
 48  use defs_abitypes
 49  use m_errors
 50  use m_xmpi
 51  use m_cgtools, only :dotprod_g
 52  use m_fock
 53  use m_hamiltonian, only : gs_hamiltonian_type
 54  use defs_datatypes, only: pseudopotential_type
 55 
 56 !This section has been created automatically by the script Abilint (TD).
 57 !Do not modify the following lines by hand.
 58 #undef ABI_FUNC
 59 #define ABI_FUNC 'fock_ACE_getghc'
 60 !End of the abilint section
 61 
 62  implicit none
 63 
 64 !Arguments ------------------------------------
 65 ! Scalars
 66  type(MPI_type),intent(in) :: mpi_enreg
 67  type(gs_hamiltonian_type),target,intent(inout) :: gs_ham
 68 ! Arrays
 69  real(dp),intent(inout) :: cwavef(:,:)!,ghc(2,gs_ham%npw_k)
 70  real(dp),intent(inout) :: ghc(:,:)
 71 
 72 !Local variables-------------------------------
 73 ! Scalars
 74  integer :: iband,ikpt,ipw,my_nspinor,nband_k,npw
 75  real(dp) :: doti,dotr,eigen
 76  type(fock_common_type),pointer :: fockcommon
 77 ! Arrays
 78  real(dp), allocatable :: ghc1(:,:),xi(:,:)
 79 
 80 
 81 ! *************************************************************************
 82 
 83  ABI_CHECK(associated(gs_ham%fockcommon),"fock must be associated!")
 84  fockcommon => gs_ham%fockcommon
 85 
 86  ABI_CHECK(gs_ham%nspinor==1,"only allowed for nspinor=1!")
 87  ABI_CHECK(gs_ham%npw_k==gs_ham%npw_kp,"only allowed for npw_k=npw_kp (ground state)!")
 88 
 89  ikpt=fockcommon%ikpt
 90  npw=gs_ham%npw_k
 91  nband_k=fockcommon%nband(ikpt)
 92  my_nspinor=max(1,gs_ham%nspinor/mpi_enreg%nproc_spinor)
 93 !*Initialization of the array ghc1
 94 !*ghc1 will contain the exact exchange contribution to the Hamiltonian
 95  ABI_ALLOCATE(ghc1,(2,npw*my_nspinor))
 96  ghc1=zero
 97  ABI_ALLOCATE(xi,(2,npw*my_nspinor))
 98 
 99  do iband=1, nband_k
100    xi(1,:)=gs_ham%fockACE_k%xi(1,:,iband)
101    xi(2,:)=gs_ham%fockACE_k%xi(2,:,iband)
102 
103    call dotprod_g(dotr,doti,gs_ham%istwf_k,npw*my_nspinor,2,xi,cwavef,mpi_enreg%me_g0,mpi_enreg%comm_fft)
104 
105    ghc1(1,:)=ghc1(1,:)-(dotr*gs_ham%fockACE_k%xi(1,:,iband)-doti*gs_ham%fockACE_k%xi(2,:,iband))
106    ghc1(2,:)=ghc1(2,:)-(dotr*gs_ham%fockACE_k%xi(2,:,iband)+doti*gs_ham%fockACE_k%xi(1,:,iband))
107  end do
108  ABI_DEALLOCATE(xi)
109 
110 !* If the calculation is parallelized, perform an MPI_allreduce to sum all the contributions in the array ghc
111 ! ghc(:,:)=ghc(:,:)/mpi_enreg%nproc_kpt + ghc1(:,:)
112  ghc(:,:)=ghc(:,:) + ghc1(:,:)
113 
114 ! call xmpi_sum(ghc,mpi_enreg%comm_kpt,ier)
115 
116 ! ============================================
117 ! === Calculate the contribution to energy ===
118 ! ============================================
119 !* Only the contribution when cwavef=cgocc_bz are calculated, in order to cancel exactly the self-interaction
120 !* at each convergence step. (consistent definition with the defintion of hartree energy)
121  if (fockcommon%ieigen/=0) then
122    eigen=zero
123 !* Dot product of cwavef and ghc
124 !* inspired from the routine 53_spacepar/meanvalue_g but without the reference to parallelism and filtering
125    if(gs_ham%istwf_k==2) then
126      eigen=half*cwavef(1,1)*ghc1(1,1)
127    else
128      eigen=cwavef(1,1)*ghc1(1,1)+cwavef(2,1)*ghc1(2,1)
129    end if
130    do ipw=2,npw
131      eigen=eigen+cwavef(1,ipw)*ghc1(1,ipw)+cwavef(2,ipw)*ghc1(2,ipw)
132    end do
133    if(gs_ham%istwf_k>=2) eigen=two*eigen
134 !   call xmpi_sum(eigen,mpi_enreg%comm_kpt,ier)
135    fockcommon%eigen_ikpt(fockcommon%ieigen)= eigen
136    fockcommon%ieigen = 0
137  end if
138 
139 ! ===============================
140 ! === Deallocate local arrays ===
141 ! ===============================
142 
143  ABI_DEALLOCATE(ghc1)
144 
145 end subroutine fock_ACE_getghc