mirror of https://gitlab.com/QEF/q-e.git
158 lines
4.6 KiB
Fortran
158 lines
4.6 KiB
Fortran
!
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! Copyright (C) 2003 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 A_h(e,h,ah)
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!-----------------------------------------------------------------------
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#include "f_defs.h"
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USE kinds, only: DP
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USE cell_base,ONLY : alat, omega, tpiba2
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USE uspp, ONLY : vkb, nkb
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USE lsda_mod, ONLY : current_spin, nspin
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USE wvfct, ONLY: nbnd, npwx, npw, g2kin, igk
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USE wavefunctions_module, ONLY: evc, psic
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USE scf, ONLY : vrs, rho
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USE gvect, ONLY : gstart, nl, nlm, nr1, nr2, nr3, nrx1, nrx2, nrx3, &
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nrxx, ngm, g, gg
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USE constants, ONLY: degspin, e2, fpi
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use becmod, only: rbecp
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use cgcom
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use funct
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!
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implicit none
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integer :: j, jkb, ibnd, na,nt,ih
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real(kind=DP) :: e(nbnd)
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complex(kind=DP) :: h(npwx,nbnd), ah(npwx,nbnd)
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!
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complex(kind=DP) :: fp, fm
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complex(kind=DP), pointer :: dpsic(:), drhoc(:), dvxc(:)
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real(kind=DP), pointer :: dv(:), drho(:)
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!
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call start_clock('a_h')
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!
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drho => auxr
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dpsic => aux2
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drhoc => aux3
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!
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drho(:) = 0.d0
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!
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! [(k+G)^2 - e ]psi
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do ibnd = 1,nbnd
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! set to zero the imaginary part of h at G=0
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! needed for numerical stability
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if (gstart==2) h(1,ibnd) = cmplx(DREAL(h(1,ibnd)),0.d0)
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do j = 1,npw
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ah(j,ibnd) = (g2kin(j)-e(ibnd)) * h(j,ibnd)
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end do
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end do
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! V_Loc psi
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do ibnd = 1,nbnd, 2
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dpsic(:)= (0.d0, 0.d0)
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psic(:) = (0.d0, 0.d0)
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if (ibnd.lt.nbnd) then
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! two ffts at the same time
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do j = 1,npw
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psic (nl (igk(j))) = evc(j,ibnd) + (0.0,1.d0)* evc(j,ibnd+1)
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dpsic(nl (igk(j))) = h(j,ibnd) + (0.0,1.d0)* h(j,ibnd+1)
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psic (nlm(igk(j)))= conjg(evc(j,ibnd)-(0.0,1.d0)* evc(j,ibnd+1))
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dpsic(nlm(igk(j)))= conjg( h(j,ibnd)-(0.0,1.d0)* h(j,ibnd+1))
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end do
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else
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do j = 1,npw
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psic (nl (igk(j))) = evc(j,ibnd)
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dpsic(nl (igk(j))) = h(j,ibnd)
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psic (nlm(igk(j))) = conjg( evc(j,ibnd))
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dpsic(nlm(igk(j))) = conjg( h(j,ibnd))
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end do
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end if
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call cft3s( psic,nr1,nr2,nr3,nrx1,nr2,nr3,2)
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call cft3s(dpsic,nr1,nr2,nr3,nrx1,nr2,nr3,2)
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do j = 1,nrxx
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drho(j) = drho(j) - 2.0*degspin/omega * &
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DREAL(psic(j)*conjg(dpsic(j)))
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dpsic(j) = dpsic(j) * vrs(j,current_spin)
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end do
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call cft3s(dpsic,nr1,nr2,nr3,nrx1,nr2,nr3,-2)
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if (ibnd.lt.nbnd) then
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! two ffts at the same time
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do j = 1,npw
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fp = (dpsic (nl(igk(j))) + dpsic (nlm(igk(j))))*0.5d0
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fm = (dpsic (nl(igk(j))) - dpsic (nlm(igk(j))))*0.5d0
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ah(j,ibnd ) = ah(j,ibnd) +cmplx(DREAL(fp), DIMAG(fm))
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ah(j,ibnd+1) = ah(j,ibnd+1)+cmplx(DIMAG(fp),-DREAL(fm))
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end do
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else
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do j = 1,npw
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ah(j,ibnd) = ah(j,ibnd) + dpsic (nl(igk(j)))
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end do
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end if
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end do
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!
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nullify(dpsic)
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! V_NL psi
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call pw_gemm ('Y', nkb, nbnd, npw, vkb, npwx, h, npwx, rbecp, nkb)
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if (nkb.gt.0) call add_vuspsi (npwx, npw, nbnd, h, ah)
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!
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do j = 1,nrxx
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drhoc(j) = DCMPLX(drho(j),0.d0)
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end do
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call cft3(drhoc,nr1,nr2,nr3,nrx1,nr2,nr3,-1)
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!
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! drho is deltarho(r), drhoc is deltarho(g)
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!
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! mu'(n(r)) psi(r) delta psi(r)
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!
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dvxc => aux2
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do j = 1,nrxx
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dvxc(j) = drho(j)*dmuxc(j)
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end do
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!
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! add gradient correction contribution (if any)
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!
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call start_clock('dgradcorr')
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if (igcx.ne.0.or.igcc.ne.0) call dgradcor1 &
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(rho, grho, dvxc_rr, dvxc_sr, dvxc_ss, dvxc_s, &
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drho, drhoc, nr1,nr2,nr3, nrx1, nrx2, nrx3, nrxx, nspin, &
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nl, nlm, ngm, g, alat, omega, dvxc)
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call stop_clock('dgradcorr')
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nullify (drho)
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!
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! 1/|r-r'| * psi(r') delta psi(r')
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!
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! gstart is the first nonzero G vector (needed for parallel execution)
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!
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if (gstart==2) drhoc(nl(1)) = 0.d0
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!
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do j = gstart,ngm
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drhoc(nl (j)) = e2*fpi*drhoc(nl(j))/ (tpiba2*gg(j))
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drhoc(nlm(j)) = conjg(drhoc(nl (j)))
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end do
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call cft3(drhoc,nr1,nr2,nr3,nrx1,nr2,nr3,+1)
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!
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! drhoc now contains deltaV_hartree
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!
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dv => auxr
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do j = 1,nrxx
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dv(j) = - DREAL(dvxc(j)) - DREAL(drhoc(j))
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end do
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!
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call vloc_psi(npwx, npw, nbnd, evc, dv, ah)
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!
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! set to zero the imaginary part of ah at G=0
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! needed for numerical stability
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if (gstart.eq.2) then
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do ibnd = 1, nbnd
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ah(1,ibnd) = cmplx(DREAL(ah(1,ibnd)),0.d0)
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end do
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end if
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!
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call stop_clock('a_h')
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!
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return
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end subroutine A_h
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