!
! Copyright (C) 2001-2003 PWSCF group
! This file is distributed under the terms of the
! GNU General Public License. See the file `License'
! in the root directory of the present distribution,
! or http://www.gnu.org/copyleft/gpl.txt .
!
!
!----------------------------------------------------------------------
subroutine dvpsi_e (kpoint, ipol)
!----------------------------------------------------------------------
!
! On output: dvpsi contains P_c^+ x | psi_kpoint > in crystal axis
! (projected on at(*,ipol) )
!
! dvpsi is READ from file if this_pcxpsi_is_on_file(kpoint,ipol)=.true.
! otherwise dvpsi is COMPUTED and WRITTEN on file (vkb,evc,igk must be set)
!
#include "f_defs.h"
!
USE ions_base, ONLY : nat, ityp, ntyp => nsp
USE io_global, ONLY : stdout
use pwcom
USE wavefunctions_module, ONLY: evc
USE kinds, only : DP
USE becmod, ONLY: becp
USE uspp_param, ONLY: nh
use phcom
implicit none
!
integer, intent(IN) :: ipol, kpoint
!
! Local variables
!
integer :: ig, na, ibnd, jbnd, ikb, jkb, nt, lter, ih, jh, ijkb0, nrec
! counters
real(kind=DP), allocatable :: gk (:,:), h_diag (:,:), eprec (:)
! the derivative of |k+G|
real(kind=DP) :: anorm, thresh
! preconditioning cut-off
! the desired convergence of linter
logical :: conv_root
! true if convergence has been achieved
complex(kind=DP), allocatable :: ps (:,:), dvkb (:,:), dvkb1 (:,:), &
work (:,:), becp2(:,:), spsi(:,:)
complex(kind=DP), external :: ZDOTC
! the scalar products
external ch_psi_all, cg_psi
!
!
call start_clock ('dvpsi_e')
if (this_pcxpsi_is_on_file(kpoint,ipol)) then
nrec = (ipol - 1)*nksq + kpoint
call davcio(dvpsi, lrebar, iuebar, nrec, -1)
call stop_clock ('dvpsi_e')
return
end if
!
if (nkb > 0) then
allocate (work ( npwx, nkb))
else
allocate (work ( npwx, 1))
endif
allocate (gk ( 3, npwx))
allocate (h_diag( npwx , nbnd))
allocate (ps ( 2 , nbnd))
allocate (spsi ( npwx, nbnd))
allocate (eprec ( nbnd))
if (nkb > 0) then
allocate (becp2 (nkb, nbnd), dvkb (npwx, nkb), dvkb1(npwx, nkb))
dvkb (:,:) = (0.d0, 0.d0)
dvkb1(:,:) = (0.d0, 0.d0)
dvpsi(:,:) = (0.d0, 0.d0)
end if
do ig = 1, npw
gk (1, ig) = (xk (1, kpoint) + g (1, igk (ig) ) ) * tpiba
gk (2, ig) = (xk (2, kpoint) + g (2, igk (ig) ) ) * tpiba
gk (3, ig) = (xk (3, kpoint) + g (3, igk (ig) ) ) * tpiba
g2kin (ig) = gk (1, ig) **2 + gk (2, ig) **2 + gk (3, ig) **2
enddo
!
! this is the kinetic contribution to [H,x]: -2i (k+G)_ipol * psi
!
do ibnd = 1, nbnd_occ (kpoint)
do ig = 1, npw
dpsi (ig, ibnd) = (at(1, ipol) * gk(1, ig) + &
at(2, ipol) * gk(2, ig) + &
at(3, ipol) * gk(3, ig) ) &
*(0.d0,-2.d0)*evc (ig, ibnd)
enddo
enddo
!
! and this is the contribution from nonlocal pseudopotentials
!
call gen_us_dj (kpoint, dvkb)
call gen_us_dy (kpoint, at (1, ipol), dvkb1)
do ig = 1, npw
if (g2kin (ig) < 1.0d-10) then
gk (1, ig) = 0.d0
gk (2, ig) = 0.d0
gk (3, ig) = 0.d0
else
gk (1, ig) = gk (1, ig) / sqrt (g2kin (ig) )
gk (2, ig) = gk (2, ig) / sqrt (g2kin (ig) )
gk (3, ig) = gk (3, ig) / sqrt (g2kin (ig) )
endif
enddo
jkb = 0
do nt = 1, ntyp
do na = 1, nat
if (nt == ityp (na)) then
do ikb = 1, nh (nt)
jkb = jkb + 1
do ig = 1, npw
work (ig,jkb) = dvkb1 (ig, jkb) + dvkb (ig, jkb) * &
(at (1, ipol) * gk (1, ig) + &
at (2, ipol) * gk (2, ig) + &
at (3, ipol) * gk (3, ig) )
enddo
enddo
endif
enddo
enddo
call ccalbec (nkb, npwx, npw, nbnd, becp2, work, evc)
ijkb0 = 0
do nt = 1, ntyp
do na = 1, nat
if (nt == ityp (na)) then
do ih = 1, nh (nt)
ikb = ijkb0 + ih
ps(:,:)=(0.d0,0.d0)
do jh = 1, nh (nt)
jkb = ijkb0 + jh
do ibnd = 1, nbnd_occ (kpoint)
ps (1, ibnd) = ps(1,ibnd)+ becp2(jkb,ibnd)* &
(0.d0,-1.d0)*(deeq(ih,jh,na,current_spin) &
-et(ibnd,kpoint)*qq(ih,jh,nt))
ps (2, ibnd) = ps(2,ibnd) +becp1(jkb,ibnd,kpoint) * &
(0.d0,-1.d0)*(deeq(ih,jh,na,current_spin)&
-et(ibnd,kpoint)*qq(ih,jh,nt))
enddo
enddo
do ibnd = 1, nbnd_occ (kpoint)
call ZAXPY(npw,ps(1,ibnd),vkb(1,ikb),1,dpsi(1,ibnd),1)
call ZAXPY(npw,ps(2,ibnd),work(1,ikb),1,dpsi(1,ibnd),1)
enddo
enddo
ijkb0=ijkb0+nh(nt)
end if
end do
end do
if (jkb /= nkb) call errore ('dvpsi_e', 'unexpected error', 1)
!
! orthogonalize dpsi to the valence subspace
!
do ibnd = 1, nbnd_occ (kpoint)
work (:,1) = (0.d0, 0.d0)
do jbnd = 1, nbnd_occ (kpoint)
ps (1, jbnd) = - ZDOTC(npw,evc(1,jbnd),1,dpsi(1, ibnd),1)
enddo
#ifdef __PARA
call reduce (4 * nbnd, ps)
#endif
do jbnd = 1, nbnd_occ (kpoint)
call ZAXPY (npw, ps (1, jbnd), evc (1, jbnd), 1, work, 1)
enddo
call ccalbec (nkb, npwx, npw, 1, becp, vkb, work)
call s_psi (npwx, npw, 1, work, spsi)
call DAXPY (2 * npw, 1.0d0, spsi, 1, dpsi (1, ibnd), 1)
enddo
!
! dpsi contains now P^+_c [H-eS,x] psi_v for the three crystal
! polarizations
! Now solve the linear systems (H-e_vS)*P_c(x*psi_v)=P_c^+ [H-e_vS,x]*psi_v
!
thresh = 1.d-5
do ibnd = 1, nbnd_occ (kpoint)
conv_root = .true.
do ig = 1, npwq
work (ig,1) = g2kin (ig) * evc (ig, ibnd)
enddo
eprec (ibnd) = 1.35d0 * ZDOTC (npwq, evc (1, ibnd), 1, work, 1)
enddo
#ifdef __PARA
call reduce (nbnd_occ (kpoint), eprec)
#endif
do ibnd = 1, nbnd_occ (kpoint)
do ig = 1, npwq
h_diag (ig, ibnd) = 1.d0 / max (1.0d0, g2kin (ig) / eprec (ibnd) )
enddo
enddo
!
call cgsolve_all (ch_psi_all, cg_psi, et (1, kpoint), dpsi, dvpsi, &
h_diag, npwx, npw, thresh, kpoint, lter, conv_root, anorm, &
nbnd_occ (kpoint) )
if (.not.conv_root) WRITE( stdout, '(5x,"kpoint",i4," ibnd",i4, &
& " linter: root not converged ",e10.3)') &
kpoint, ibnd, anorm
#ifdef FLUSH
call flush (6)
#endif
!
! we have now obtained P_c x |psi>.
! In the case of USPP this quantity is needed for the Born
! effective charges, so we save it to disc
!
! In the US case we obtain P_c x |psi>, but we need P_c^+ x | psi>,
! therefore we apply S again, and then subtract the additional term
! furthermore we add the term due to dipole of the augmentation charges.
!
if (okvan) then
!
! for effective charges
!
nrec = (ipol - 1) * nksq + kpoint
call davcio (dvpsi, lrcom, iucom, nrec, 1)
!
call ccalbec(nkb,npwx,npw,nbnd,becp,vkb,dvpsi)
call s_psi(npwx,npw,nbnd,dvpsi,spsi)
call DCOPY(2*npwx*nbnd,spsi,1,dvpsi,1)
call adddvepsi_us(becp2,ipol,kpoint)
endif
if (nkb > 0) deallocate (dvkb1, dvkb, becp2)
deallocate (eprec)
deallocate (spsi)
deallocate (ps)
deallocate (h_diag)
deallocate (gk)
deallocate (work)
nrec = (ipol - 1)*nksq + kpoint
call davcio(dvpsi, lrebar, iuebar, nrec, 1)
this_pcxpsi_is_on_file(kpoint,ipol) = .true.
call stop_clock ('dvpsi_e')
return
end subroutine dvpsi_e