mirror of https://gitlab.com/QEF/q-e.git
67 lines
1.9 KiB
Fortran
67 lines
1.9 KiB
Fortran
!
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! Copyright (C) 2001-2018 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 swfc (npw_, nbnd_, vkb_, wfc_, swfc_)
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!---------------------------------------------------------------
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!! This routine applies the S operator to the function \(\text{wfc_}\)
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!! and puts the result in \(\text{swfc_}\), i.e.
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!! \(\text{swfc_} = S * \text{wfc_}\).
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!
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!! Important notice: here, the global array \(\text{vkb}\) is used as
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!! a workspace, because the routine \(\texttt{s_psi}\) uses
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!! \(\text{vkb}\) internally.
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!! \(\text{vkb_}\) can be a beta function at k or k+q, therefore,
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!! before changing the global array \(\text{vkb}\), we need to be very
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!! careful: save \(\text{vkb}\) to a temporary array \(\text{vkb_save}\).
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!! Then we copy \(\text{vkb_save}\) back to \(\text{vkb}\), such that
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!! the meaning of \(\text{vkb}\) outside of this routine is restored
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!! (whatever it is).
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!
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!! Written by A. Floris.
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!! Modified by I. Timrov (01.10.2018).
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!
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USE kinds, ONLY : DP
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USE becmod, ONLY : becp, calbec
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USE uspp, ONLY : vkb, nkb
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USE wvfct, ONLY : npwx
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IMPLICIT NONE
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INTEGER, INTENT(IN) :: npw_
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INTEGER, INTENT(IN) :: nbnd_
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COMPLEX(DP), INTENT(IN) :: vkb_ (npwx, nkb)
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COMPLEX(DP), INTENT(IN) :: wfc_ (npwx, nbnd_)
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COMPLEX(DP), INTENT(OUT) :: swfc_(npwx, nbnd_)
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!
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COMPLEX(DP), ALLOCATABLE :: vkb_save(:,:)
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!
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CALL start_clock( 'swfc' )
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!
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swfc_ = (0.d0, 0.d0)
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!
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ALLOCATE(vkb_save(npwx,nkb))
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!
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vkb_save = vkb
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vkb = vkb_
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!
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CALL calbec (npw_, vkb, wfc_, becp)
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!
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! s_psi uses vkb
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!
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CALL s_psi (npwx, npw_, nbnd_, wfc_, swfc_)
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!
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vkb = vkb_save
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!
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CALL stop_clock( 'swfc' )
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!
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RETURN
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!
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END SUBROUTINE swfc
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