mirror of https://gitlab.com/QEF/q-e.git
100 lines
2.7 KiB
Fortran
100 lines
2.7 KiB
Fortran
!
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! Copyright (C) 2001 PWSCF 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 h_psiq_vdw (lda, n, m, psi, hpsi, spsi)
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!-----------------------------------------------------------------------
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!
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! This routine computes the product of the Hamiltonian
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! and of the S matrix with a m wavefunctions contained
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! in psi. It first computes the bec matrix of these
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! wavefunctions and then with the routines hus_1psi and
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! s_psi computes for each band the required products
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!
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USE fft_base, ONLY : dffts
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USE fft_interfaces, ONLY : fwfft, invfft
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USE pwcom
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USE scf, ONLY : vrs
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USE wavefunctions_module, ONLY: psic
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USE becmod, ONLY: becp
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USE kinds, ONLY : DP
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USE phcom
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IMPLICIT NONE
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!
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! Here the local variables
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!
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INTEGER :: ibnd
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! counter on bands
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INTEGER :: lda, n, m
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! input: the leading dimension of the array psi
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! input: the real dimension of psi
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! input: the number of psi to compute
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INTEGER :: j
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! do loop index
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COMPLEX(kind=DP) :: psi (lda, m), hpsi (lda, m), spsi (lda, m)
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! input: the functions where to apply H and S
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! output: H times psi
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! output: S times psi (Us PP's only)
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CALL start_clock ('h_psiq')
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CALL start_clock ('init')
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! call calbec ( n, vkb, psi, becp, m) ! no need in TFvW
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!
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! Here we apply the kinetic energy (k+G)^2 psi
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!
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DO ibnd = 1, m
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DO j = 1, n
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hpsi (j, ibnd) = g2kin (j) * psi (j, ibnd)
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ENDDO
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ENDDO
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CALL stop_clock ('init')
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!
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! the local potential V_Loc psi. First the psi in real space
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!
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DO ibnd = 1, m
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CALL start_clock ('firstfft')
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psic(:) = (0.d0, 0.d0)
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DO j = 1, n
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psic (nls(igkq(j))) = psi (j, ibnd)
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ENDDO
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CALL invfft ('Wave', psic, dffts)
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CALL stop_clock ('firstfft')
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!
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! and then the product with the potential vrs = (vltot+vr) on the smoo
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!
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DO j = 1, dffts%nnr
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psic (j) = psic (j) * vrs (j, current_spin)
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ENDDO
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!
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! back to reciprocal space
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!
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CALL start_clock ('secondfft')
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CALL fwfft ('Wave', psic, dffts)
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!
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! addition to the total product
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!
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DO j = 1, n
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hpsi (j, ibnd) = hpsi (j, ibnd) + psic (nls(igkq(j)))
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ENDDO
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CALL stop_clock ('secondfft')
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ENDDO
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!
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! Here the product with the non local potential V_NL psi
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!
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! call add_vuspsi (lda, n, m, hpsi) ! no need in TFvW
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CALL s_psi (lda, n, m, psi, spsi) ! no need in TFvW
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CALL stop_clock ('h_psiq')
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RETURN
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END SUBROUTINE h_psiq_vdw
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