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ABINIT/dsdr_k_paw [ Functions ]

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NAME

 dsdr_k_paw

FUNCTION

 compute on-site terms for forces and stresses for finite electric fields with PAW

COPYRIGHT

 Copyright (C) 2005-2018 ABINIT group
 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

  cprj_k (pawcprj_type) :: cprj for occupied bands at point k
  cprj_kb :: cprj for occupied bands at point k+b
  dtefield :: structure referring to all efield and berry's phase variables
  kdir :: integer giving direction along which overlap is computed for ket
  kfor :: integer indicating whether to compute forward (1) or backward (2)
    along kpt string
  natom :: number of atoms in cell
  typat :: typat(natom) type of each atom

OUTPUT

SIDE EFFECTS

 dsdr :: array of the on-site PAW parts of the derivatives with respect to atm
               positions and/or strains of the overlaps between Bloch states at points
               k and k+b, for the various pairs of bands

NOTES

 This routine assumes that the cprj are not explicitly ordered by 
 atom type.

PARENTS

      berryphase_new

CHILDREN

SOURCE

 43 #if defined HAVE_CONFIG_H
 44 #include "config.h"
 45 #endif
 46 
 47 #include "abi_common.h"
 48 
 49  subroutine dsdr_k_paw(cprj_k,cprj_kb,dsdr,dtefield,kdir,kfor,mband,natom,ncpgr,typat)
 50 
 51  use m_profiling_abi
 52 
 53  use defs_basis
 54  use m_errors
 55  use m_efield
 56  use m_pawcprj, only : pawcprj_type
 57 
 58 !This section has been created automatically by the script Abilint (TD).
 59 !Do not modify the following lines by hand.
 60 #undef ABI_FUNC
 61 #define ABI_FUNC 'dsdr_k_paw'
 62 !End of the abilint section
 63 
 64  implicit none
 65 
 66 !Arguments---------------------------
 67 !scalars
 68  integer,intent(in) :: kdir,kfor,mband,natom,ncpgr
 69  character(len=500) :: message
 70  type(efield_type),intent(in) :: dtefield
 71  type(pawcprj_type),intent(in) :: cprj_k(natom,dtefield%nspinor*mband)
 72  type(pawcprj_type),intent(in) :: cprj_kb(natom,dtefield%nspinor*mband)
 73 
 74 !arrays
 75  integer,intent(in) :: typat(natom)
 76  real(dp),intent(inout) :: dsdr(2,natom,ncpgr,dtefield%mband_occ,dtefield%mband_occ)
 77 
 78 !Local variables---------------------------
 79 !scalars
 80  integer :: iatom,iband,ibs,icpgr,ilmn,ispinor,itypat
 81  integer :: jband,jbs,jlmn,klmn,nspinor
 82  complex(dpc) :: cpk,cpkb,dcpk,dcpkb,cterm,paw_onsite
 83 
 84 ! *************************************************************************
 85 
 86 !initialize dsdr
 87  dsdr(:,:,:,:,:) = zero
 88 
 89 ! if 3 gradients we are in the ctocprj choice 2 case
 90 ! and the 3 gradients are due to the atomic displacements
 91 ! if 6 gradients we are in the ctocprj choice 3 case
 92 ! and the 6 gradients are due to the strains
 93 ! if 9 gradients we are in the ctocprj choice 23 case
 94 ! and the first six are due to strain, last three due to displacements
 95  if (ncpgr /= 3 .and. ncpgr /= 6 .and. ncpgr /= 9) then
 96    message = ' dsdr_k_paw called with ncpgr /= 3, 6, or 9 (no gradients) '
 97    MSG_BUG(message)
 98  end if
 99  
100  nspinor = dtefield%nspinor
101 
102  do iatom = 1, natom
103    itypat = typat(iatom)
104 
105    do ilmn=1,dtefield%lmn_size(itypat)
106      do jlmn=1,dtefield%lmn_size(itypat)
107        klmn=max(ilmn,jlmn)*(max(ilmn,jlmn)-1)/2 + min(ilmn,jlmn)
108        paw_onsite = cmplx(dtefield%qijb_kk(1,klmn,iatom,kdir),&
109 &       dtefield%qijb_kk(2,klmn,iatom,kdir))
110        if (kfor > 1) paw_onsite = conjg(paw_onsite)
111        do iband = 1, dtefield%mband_occ
112          do jband = 1, dtefield%mband_occ
113            do ispinor = 1, nspinor
114              do icpgr = 1, ncpgr
115                ibs = nspinor*(iband-1) + ispinor
116                jbs = nspinor*(jband-1) + ispinor
117                cpk=cmplx(cprj_k(iatom,ibs)%cp(1,ilmn),cprj_k(iatom,ibs)%cp(2,ilmn))
118                dcpk=cmplx(cprj_k(iatom,ibs)%dcp(1,icpgr,ilmn),cprj_k(iatom,ibs)%dcp(2,icpgr,ilmn))
119                cpkb=cmplx(cprj_kb(iatom,jbs)%cp(1,jlmn),cprj_kb(iatom,jbs)%cp(2,jlmn))
120                dcpkb=cmplx(cprj_kb(iatom,jbs)%dcp(1,icpgr,jlmn),cprj_kb(iatom,jbs)%dcp(2,icpgr,jlmn))
121                cterm=paw_onsite*(conjg(dcpk)*cpkb+conjg(cpk)*dcpkb)
122                dsdr(1,iatom,icpgr,iband,jband) = dsdr(1,iatom,icpgr,iband,jband)+real(cterm)
123                dsdr(2,iatom,icpgr,iband,jband) = dsdr(2,iatom,icpgr,iband,jband)+aimag(cterm)
124              end do ! end loop over icpgr
125            end do ! end loop over ispinor
126          end do ! end loop over jband
127        end do ! end loop over iband
128      end do ! end loop over ilmn
129    end do ! end loop over jlmn
130 
131  end do ! end loop over atoms
132 
133  end subroutine    dsdr_k_paw