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ABINIT/overlap_k1k2_paw [ Functions ]

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NAME

 overlap_k1k2_paw

FUNCTION

 compute PAW overlap between two k points,
 similar to smatrix_k_paw.F90 but more generic

COPYRIGHT

 Copyright (C) 2005-2017 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_k1 (pawcprj_type) :: cprj for occupied bands at point k1
  cprj_k2 :: cprj for occupied bands at point k2
  dk(3) :: vector k2 - k1
  gprimd(3,3)=dimensioned primitive translations of reciprocal lattice
  lmn2max :: lmnmax*(lmnmax+1)/2
  lmnsize(ntypat) :: lmnsize for each atom type
  mband :: number of bands
  natom=number of atoms in unit cell
  nspinor :: number of spinors (1 or 2)
  ntypat=number of types of atoms in unit cell
  pawang <type(pawang_type)>=paw angular mesh and related data
  pawrad(ntypat) <type(pawrad_type)>=paw radial mesh and related data
  pawtab(ntypat) <type(pawtab_type)>=paw tabulated starting data
  typat=typat(natom) list of atom types
  xred(natom,3) :: locations of atoms in cell

OUTPUT

 k1k2_paw(2,mband,mband) :: array of the on-site PAW parts of the overlaps between Bloch states at points
   k1 and k2, for the various pairs of bands, that is, the on-site part of 
   <u_nk1|u_mk2>

SIDE EFFECTS

NOTES

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

PARENTS

      chern_number

CHILDREN

      expibi,qijb_kk

SOURCE

 52 #if defined HAVE_CONFIG_H
 53 #include "config.h"
 54 #endif
 55 
 56 #include "abi_common.h"
 57 
 58 subroutine overlap_k1k2_paw(cprj_k1,cprj_k2,dk,gprimd,k1k2_paw,lmn2max,lmnsize,mband,&
 59 &                           natom,nspinor,ntypat,pawang,pawrad,pawtab,typat,xred)
 60 
 61  use m_profiling_abi
 62 
 63  use defs_basis
 64  use m_errors
 65  use m_pawang, only : pawang_type
 66  use m_pawcprj, only : pawcprj_type
 67  use m_pawrad, only : pawrad_type
 68  use m_pawtab, only : pawtab_type
 69 
 70 !This section has been created automatically by the script Abilint (TD).
 71 !Do not modify the following lines by hand.
 72 #undef ABI_FUNC
 73 #define ABI_FUNC 'overlap_k1k2_paw'
 74  use interfaces_65_paw, except_this_one => overlap_k1k2_paw
 75 !End of the abilint section
 76 
 77  implicit none
 78 
 79 !Arguments---------------------------
 80 !scalars
 81  integer,intent(in) :: lmn2max,mband,natom,nspinor,ntypat
 82  type(pawang_type),intent(in) :: pawang
 83  type(pawcprj_type),intent(in) :: cprj_k1(natom,mband),cprj_k2(natom,mband)
 84 
 85 !arrays
 86  integer,intent(in) :: lmnsize(ntypat),typat(natom)
 87  real(dp),intent(in) :: dk(3),gprimd(3,3),xred(natom,3)
 88  real(dp),intent(out) :: k1k2_paw(2,mband,mband)
 89  type(pawrad_type),intent(in) :: pawrad(ntypat)
 90  type(pawtab_type),intent(in) :: pawtab(ntypat)
 91 
 92 !Local variables---------------------------
 93 !scalars
 94  integer :: iatom,iband,ibs,ilmn,ispinor,itypat
 95  integer :: jband,jbs,jlmn,klmn
 96  complex(dpc) :: cpk1,cpk2,cterm,paw_onsite
 97 
 98  ! arrays
 99  real(dp),allocatable :: calc_expibi(:,:),calc_qijb(:,:,:)
100 
101 ! *************************************************************************
102 
103 !initialize k1k2_paw output variable
104  k1k2_paw(:,:,:) = zero
105 
106  ! obtain the atomic phase factors for the input k vector shift
107  ABI_ALLOCATE(calc_expibi,(2,natom))
108  call expibi(calc_expibi,dk,natom,xred)
109 
110  ! obtain the onsite PAW terms for the input k vector shift
111  ABI_ALLOCATE(calc_qijb,(2,lmn2max,natom))
112  call qijb_kk(calc_qijb,dk,calc_expibi,gprimd,lmn2max,natom,ntypat,pawang,pawrad,pawtab,typat)
113  ABI_DEALLOCATE(calc_expibi)
114 
115  do iatom = 1, natom
116    itypat = typat(iatom)
117 
118    do ilmn=1,lmnsize(itypat)
119      do jlmn=1,lmnsize(itypat)
120        klmn=max(ilmn,jlmn)*(max(ilmn,jlmn)-1)/2 + min(ilmn,jlmn)
121        paw_onsite = cmplx(calc_qijb(1,klmn,iatom),calc_qijb(2,klmn,iatom))
122        do iband = 1, mband
123          do jband = 1, mband
124            do ispinor = 1, nspinor
125              ibs = nspinor*(iband-1) + ispinor
126              jbs = nspinor*(jband-1) + ispinor
127              cpk1=cmplx(cprj_k1(iatom,ibs)%cp(1,ilmn),cprj_k1(iatom,ibs)%cp(2,ilmn))
128              cpk2=cmplx(cprj_k2(iatom,jbs)%cp(1,jlmn),cprj_k2(iatom,jbs)%cp(2,jlmn))
129              cterm = conjg(cpk1)*paw_onsite*cpk2
130              k1k2_paw(1,iband,jband) = k1k2_paw(1,iband,jband)+real(cterm)
131              k1k2_paw(2,iband,jband) = k1k2_paw(2,iband,jband)+aimag(cterm)
132            end do ! end loop over ispinor
133          end do ! end loop over jband
134        end do ! end loop over iband
135      end do ! end loop over ilmn
136    end do ! end loop over jlmn
137 
138  end do ! end loop over atoms
139 
140  ABI_DEALLOCATE(calc_qijb)
141 
142  end subroutine overlap_k1k2_paw