mirror of https://gitlab.com/QEF/q-e.git
134 lines
4.6 KiB
Fortran
134 lines
4.6 KiB
Fortran
!
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! Copyright (C) 2001 PWSCF group
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! This file is distributed under the terms of the
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! GNU General Public License. See the file `License'
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! in the root directory of the present distribution,
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! or http://www.gnu.org/copyleft/gpl.txt .
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!
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!
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!-----------------------------------------------------------------------
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subroutine compute_becsum_ph
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!-----------------------------------------------------------------------
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!
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! This routine computes the becsum term which is used to compute the
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! change of the charge due to the displacement of the augmentation
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! term.
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! It implements Eq. B16 of Ref.[1].
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! [1] PRB 64, 235118 (2001).
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!
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!
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#include "f_defs.h"
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!
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USE kinds, only : DP
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USE ions_base, ONLY : nat, ityp, ntyp => nsp
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USE lsda_mod, ONLY : current_spin, isk, lsda
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USE wvfct, ONLY : nbnd, wg
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USE noncollin_module, ONLY : noncolin, npol
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USE uspp, ONLY: okvan, becsum
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USE uspp_param, ONLY: upf, nh
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USE phus, ONLY : alphasum, alphasum_nc, becp1, becp1_nc, alphap, &
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alphap_nc, becsum_nc
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USE qpoint, ONLY : nksq, ikks, ikqs
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USE control_ph, ONLY : nbnd_occ
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implicit none
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integer :: ik, ikk, ikq, ijkb0, ijh, ikb, jkb, ih, jh, na, nt, ibnd
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! counter on k points, beta functions, atoms and bands
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integer :: ijs, is1, is2
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real(DP) :: wgg1 ! auxiliary weight
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if (.not.okvan) return
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IF (noncolin) becsum_nc = (0.d0,0.d0)
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becsum = 0.d0
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do ik = 1, nksq
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ikk = ikks(ik)
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ikq = ikqs(ik)
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if (lsda) current_spin = isk (ikk)
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ijkb0 = 0
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do nt = 1, ntyp
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if (upf(nt)%tvanp ) then
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do na = 1, nat
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if (ityp (na) == nt) then
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ijh = 0
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do ih = 1, nh (nt)
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ikb = ijkb0 + ih
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ijh = ijh + 1
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do ibnd = 1, nbnd_occ (ikk)
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wgg1 = wg (ibnd, ikk)
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IF (noncolin) THEN
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DO is1=1,npol
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DO is2=1,npol
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becsum_nc(ijh,na,is1,is2) = &
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becsum_nc(ijh,na,is1,is2) + wgg1* &
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CONJG(becp1_nc(ikb,is1,ibnd,ik))* &
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becp1_nc(ikb,is2,ibnd,ik)
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END DO
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END DO
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ELSE
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becsum(ijh,na,current_spin) = &
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becsum(ijh,na,current_spin) + wgg1 * &
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DBLE ( CONJG(becp1(ikb,ibnd,ik)) * becp1(ikb,ibnd,ik) )
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END IF
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enddo
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do jh = ih+1, nh (nt)
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jkb = ijkb0 + jh
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ijh = ijh + 1
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do ibnd = 1, nbnd
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wgg1 = wg (ibnd, ikk)
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IF (noncolin) THEN
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DO is1=1,npol
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DO is2=1,npol
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becsum_nc(ijh,na,is1,is2) = &
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becsum_nc(ijh,na,is1,is2)+ wgg1 * &
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(CONJG(becp1_nc(ikb,is1,ibnd,ik)) * &
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becp1_nc(jkb,is2,ibnd,ik) )
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END DO
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END DO
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ELSE
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becsum(ijh,na,current_spin) = &
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becsum(ijh,na,current_spin)+wgg1 * 2.d0 * &
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DBLE ( CONJG(becp1(ikb,ibnd,ik)) * &
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becp1(jkb,ibnd,ik) )
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END IF
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enddo
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enddo
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enddo
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ijkb0 = ijkb0 + nh (nt)
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endif
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enddo
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else
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do na = 1, nat
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if (ityp(na) == nt) ijkb0 = ijkb0 + nh (nt)
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enddo
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endif
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enddo
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enddo
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IF (noncolin.and.okvan) THEN
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DO nt = 1, ntyp
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IF ( upf(nt)%tvanp ) THEN
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DO na = 1, nat
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IF (ityp(na)==nt) THEN
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IF (upf(nt)%has_so) THEN
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CALL transform_becsum_so(becsum_nc,becsum,na)
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ELSE
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CALL transform_becsum_nc(becsum_nc,becsum,na)
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END IF
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END IF
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END DO
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END IF
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END DO
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END IF
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! do na=1,nat
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! nt=ityp(na)
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! do ijh=1,nh(nt)*(nh(nt)+1)/2
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! WRITE( stdout,'(2i5,f20.10)') na, ijh, becsum(ijh,na,1)
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! enddo
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! enddo
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! call stop_ph(.true.)
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return
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end subroutine compute_becsum_ph
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