mirror of https://gitlab.com/QEF/q-e.git
100 lines
3.0 KiB
Fortran
100 lines
3.0 KiB
Fortran
!
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! Copyright (C) 2001-208 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 solve_e_nscf( avg_iter, thresh, ik, ipol, dvscfs, auxr )
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!-----------------------------------------------------------------------
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!
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! Solve the linear system which defines the change of the wavefunctions
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! due to the electric field for a given k_point in a non self-consistent
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! way. The self-consistent variation of the potential has been computed
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! previously and is in dvscfs.
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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 klist, ONLY : xk
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USE fft_base, ONLY : dffts
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USE fft_interfaces, ONLY : fwfft, invfft
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USE gvect, ONLY : g
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USE gvecs, ONLY : nls
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USE wvfct, ONLY : npw, igk, g2kin, et
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USE wavefunctions_module, ONLY : evc
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USE eqv, ONLY : dpsi, dvpsi
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USE units_ph, ONLY : this_pcxpsi_is_on_file, lrdwf, iudwf
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USE qpoint, ONLY : nksq, npwq, igkq
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USE control_ph, ONLY : nbnd_occ
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implicit none
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!
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! Input variables
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!
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integer :: ik, ipol
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! input: k-point under consideration
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! input: polarization of the electric field
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real(DP) :: thresh, avg_iter
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! input: convergence threshold
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! in/out: # of diagonalization iterations
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complex(DP) :: dvscfs (dffts%nnr, 3), auxr(dffts%nnr)
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! input: potential on the smooth grid
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! auxiliary work space
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!
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! Local variables
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!
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integer :: ibnd, ir, ig, nrec
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! counter on bands
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! counter on mesh points
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! counter on G-points
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! the record number
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!
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! Calculates [H,x]*psi_kpoint
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!
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dpsi (:,:) = (0.d0, 0.d0)
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this_pcxpsi_is_on_file(:,:)=.false.
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call dvpsi_e (ik, ipol)
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do ig = 1, npw
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g2kin (ig) = ( (xk (1, ik) + g(1, igk (ig)) ) **2 + &
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(xk (2, ik) + g(2, igk (ig)) ) **2 + &
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(xk (3, ik) + g(3, igk (ig)) ) **2 ) *tpiba2
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enddo
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!
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! Calculates dvscf*psi_k in G_space,
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!
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do ibnd = 1, nbnd_occ (ik)
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auxr (:) = (0.d0, 0.d0)
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do ig = 1, npw
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auxr (nls (igk (ig))) = evc (ig, ibnd)
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end do
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CALL invfft ('Wave', auxr, dffts)
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do ir = 1, dffts%nnr
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auxr (ir) = auxr(ir) * dvscfs(ir, ipol)
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end do
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CALL fwfft ('Wave', auxr, dffts)
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do ig = 1, npwq
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dvpsi (ig, ibnd) = dvpsi(ig, ibnd) + auxr(nls (igkq (ig)))
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enddo
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enddo
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!
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! starting value for delta_psi is read from iudwf
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!
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nrec = (ipol - 1) * nksq + ik
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call davcio (dpsi, lrdwf, iudwf, nrec, -1)
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call pcgreen (avg_iter, thresh, ik, et (1, ik))
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!
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! The pcxpsi on file could be at k+dk and cannot be used by the following
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! codes that require pcxpsi at k.
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!
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this_pcxpsi_is_on_file(ik,ipol)=.false.
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return
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end subroutine solve_e_nscf
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