mirror of https://gitlab.com/QEF/q-e.git
149 lines
4.7 KiB
Fortran
149 lines
4.7 KiB
Fortran
!
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! Copyright (C) 2001-2009 Quantum ESPRESSO 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 dvpsi_e (ik, ipol)
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!----------------------------------------------------------------------
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!
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! On output: dvpsi contains P_c^+ x | psi_ik > in crystal axis
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! (projected on at(*,ipol) )
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!
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! dvpsi is READ from file if this_pcxpsi_is_on_file(ik,ipol)=.true.
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! otherwise dvpsi is COMPUTED and WRITTEN on file (vkb,evc,igk must be set)
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!
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USE kinds, ONLY : DP
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USE cell_base, ONLY : tpiba2
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USE io_global, ONLY : stdout
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USE klist, ONLY : xk
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USE gvect, ONLY : g
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USE wvfct, ONLY : npw, npwx, nbnd, igk, g2kin, et
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USE wavefunctions_module, ONLY: evc
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USE noncollin_module,ONLY : noncolin, npol
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USE becmod, ONLY : bec_type, becp, calbec, &
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allocate_bec_type, deallocate_bec_type
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USE uspp, ONLY : okvan, nkb, vkb
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USE uspp_param, ONLY : nh, nhm
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USE ramanm, ONLY : eth_rps
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USE eqv, ONLY : dpsi, dvpsi, eprec
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USE phus, ONLY : becp1
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USE qpoint, ONLY : nksq, npwq
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USE units_ph, ONLY : this_pcxpsi_is_on_file, lrcom, iucom, &
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lrebar, iuebar
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USE control_ph, ONLY : nbnd_occ
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implicit none
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!
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integer, intent(IN) :: ipol, ik
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!
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! Local variables
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!
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integer :: ig, na, ibnd, jbnd, ikb, jkb, nt, lter, ih, jh, ijkb0, &
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nrec, is, js, ijs
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! counters
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real(DP), allocatable :: h_diag (:,:)
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! the diagonal part of h_scf
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type(bec_type) :: becp2 ! the scalar products
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complex(DP), allocatable :: spsi(:,:)
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real(DP) :: anorm, thresh
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! preconditioning cut-off
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! the desired convergence of linter
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logical :: conv_root
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! true if convergence has been achieved
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external ch_psi_all, cg_psi
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!
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call start_clock ('dvpsi_e')
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dpsi=(0.d0, 0.d0)
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dvpsi=(0.d0, 0.d0)
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if (this_pcxpsi_is_on_file(ik,ipol)) then
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nrec = (ipol - 1)*nksq + ik
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call davcio(dvpsi, lrebar, iuebar, nrec, -1)
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call stop_clock ('dvpsi_e')
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return
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end if
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!
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call allocate_bec_type ( nkb, nbnd, becp2)
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! calculate the commutator [H,x_ipol] psi > and store it in dpsi
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! dvpsi used as workspace
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call commutator_Hx_psi (ik, nbnd_occ(ik), becp1(ik), becp2, ipol, dpsi, dvpsi )
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!
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! orthogonalize dpsi to the valence subspace: ps = <evc|dpsi>
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! Apply -P^+_c
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! NB it uses dvpsi as workspace
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!
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CALL orthogonalize(dpsi, evc, ik, ik, dvpsi, npwq)
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dpsi=-dpsi
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!
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! dpsi contains P^+_c [H-eS,x] psi_v for the three crystal polarizations
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! Now solve the linear systems (H-e_vS)*P_c(x*psi_v)=P_c^+ [H-e_vS,x]*psi_v
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!
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do ig = 1, npw
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g2kin (ig) = SUM((xk(1:3,ik) +g (1:3, igk (ig)) ) **2) *tpiba2
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enddo
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allocate (h_diag( npwx*npol, nbnd))
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h_diag=0.d0
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do ibnd = 1, nbnd_occ (ik)
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do ig = 1, npw
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h_diag (ig, ibnd) = 1.d0 / max (1.0d0, g2kin (ig) / eprec (ibnd,ik) )
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enddo
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IF (noncolin) THEN
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do ig = 1, npw
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h_diag (ig+npwx, ibnd) = 1.d0/max(1.0d0,g2kin(ig)/eprec(ibnd,ik))
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enddo
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END IF
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enddo
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!
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dvpsi(:,:) = (0.d0, 0.d0)
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!
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thresh = eth_rps
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call cgsolve_all (ch_psi_all, cg_psi, et (1, ik), dpsi, dvpsi, &
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h_diag, npwx, npw, thresh, ik, lter, conv_root, anorm, &
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nbnd_occ (ik), npol)
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if (.not.conv_root) WRITE( stdout, '(5x,"ik",i4," ibnd",i4, &
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& " linter: root not converged ",e10.3)') &
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ik, ibnd, anorm
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!
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CALL flush_unit( stdout )
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deallocate (h_diag)
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!
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! we have now obtained P_c x |psi>.
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! In the case of USPP this quantity is needed for the Born
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! effective charges, so we save it to disc
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!
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! In the US case we obtain P_c x |psi>, but we need P_c^+ x | psi>,
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! therefore we apply S again, and then subtract the additional term
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! furthermore we add the term due to dipole of the augmentation charges.
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!
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if (okvan) then
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!
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! for effective charges
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!
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nrec = (ipol - 1) * nksq + ik
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call davcio (dvpsi, lrcom, iucom, nrec, 1)
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!
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allocate (spsi ( npwx*npol, nbnd))
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CALL calbec (npw, vkb, dvpsi, becp )
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CALL s_psi(npwx,npw,nbnd,dvpsi,spsi)
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call dcopy(2*npwx*npol*nbnd,spsi,1,dvpsi,1)
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deallocate (spsi)
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CALL adddvepsi_us(becp1(ik),becp2,ipol,ik,dvpsi)
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endif
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IF (nkb > 0) call deallocate_bec_type (becp2)
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nrec = (ipol - 1)*nksq + ik
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call davcio(dvpsi, lrebar, iuebar, nrec, 1)
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this_pcxpsi_is_on_file(ik,ipol) = .true.
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call stop_clock ('dvpsi_e')
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return
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end subroutine dvpsi_e
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