mirror of https://gitlab.com/QEF/q-e.git
88 lines
2.4 KiB
Fortran
88 lines
2.4 KiB
Fortran
!
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! Copyright (C) 2001-2008 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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subroutine incdrhoscf (drhoscf, weight, ik, dbecsum)
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!-----------------------------------------------------------------------
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!
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! This routine computes the change of the charge density due to the
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! perturbation. It is called at the end of the computation of the
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! change of the wavefunction for a given k point.
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!
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!
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USE kinds, only : DP
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USE cell_base, ONLY : omega
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USE ions_base, ONLY : nat
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USE gsmooth, ONLY : nrxxs, nls, nr1s, nr2s, nr3s, nrx1s, nrx2s, nrx3s
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USE wvfct, ONLY : npw, igk
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USE uspp_param,ONLY: nhm
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USE wavefunctions_module, ONLY: evc
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USE eqv, ONLY : dpsi
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USE qpoint, ONLY : npwq, igkq, ikks
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USE control_ph, ONLY : nbnd_occ
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implicit none
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integer :: ik
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! input: the k point
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real(DP) :: weight
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! input: the weight of the k point
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complex(DP) :: drhoscf (nrxxs), dbecsum (nhm*(nhm+1)/2,nat)
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! output: the change of the charge densit
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! inp/out: the accumulated dbec
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!
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! here the local variable
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!
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real(DP) :: wgt
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! the effective weight of the k point
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complex(DP), allocatable :: psi (:), dpsic (:)
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! the wavefunctions in real space
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! the change of wavefunctions in real space
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integer :: ibnd, ikk, ir, ig
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! counters
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call start_clock ('incdrhoscf')
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allocate (dpsic( nrxxs))
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allocate (psi ( nrxxs))
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wgt = 2.d0 * weight / omega
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ikk = ikks(ik)
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!
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! dpsi contains the perturbed wavefunctions of this k point
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! evc contains the unperturbed wavefunctions of this k point
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!
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do ibnd = 1, nbnd_occ (ikk)
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psi (:) = (0.d0, 0.d0)
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do ig = 1, npw
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psi (nls (igk (ig) ) ) = evc (ig, ibnd)
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enddo
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call cft3s (psi, nr1s, nr2s, nr3s, nrx1s, nrx2s, nrx3s, + 2)
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dpsic(:) = (0.d0, 0.d0)
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do ig = 1, npwq
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dpsic (nls (igkq (ig) ) ) = dpsi (ig, ibnd)
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enddo
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call cft3s (dpsic, nr1s, nr2s, nr3s, nrx1s, nrx2s, nrx3s, + 2)
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do ir = 1, nrxxs
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drhoscf (ir) = drhoscf (ir) + wgt * CONJG(psi (ir) ) * dpsic (ir)
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enddo
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enddo
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call addusdbec (ik, weight, dpsi, dbecsum)
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deallocate (psi)
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deallocate (dpsic)
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call stop_clock ('incdrhoscf')
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return
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end subroutine incdrhoscf
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