mirror of https://gitlab.com/QEF/q-e.git
155 lines
4.5 KiB
Fortran
155 lines
4.5 KiB
Fortran
!
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! Copyright (C) 2001-2007 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 h_psiq (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 kinds, ONLY : DP
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USE wavefunctions_module, ONLY : psic, psic_nc
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USE becmod, ONLY : bec_type, becp, calbec
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USE noncollin_module, ONLY : noncolin, npol
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USE lsda_mod, ONLY : current_spin
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USE gsmooth, ONLY : nls, nr1s, nr2s, nr3s, nrx1s, nrx2s, nrx3s, nrxxs
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USE spin_orb, ONLY : domag
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USE scf, ONLY : vrs
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USE uspp, ONLY : vkb
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USE wvfct, ONLY : g2kin
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USE qpoint, ONLY : igkq
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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(DP) :: psi (lda*npol, m), hpsi (lda*npol, m), spsi (lda*npol, m)
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complex(DP) :: sup, sdwn
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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)
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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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hpsi=(0.d0,0.d0)
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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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IF (noncolin) THEN
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DO ibnd = 1, m
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DO j = 1, n
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hpsi (j+lda, ibnd) = g2kin (j) * psi (j+lda, ibnd)
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ENDDO
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ENDDO
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ENDIF
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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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IF (noncolin) THEN
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psic_nc = (0.d0, 0.d0)
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do j = 1, n
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psic_nc(nls(igkq(j)),1) = psi (j, ibnd)
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psic_nc(nls(igkq(j)),2) = psi (j+lda, ibnd)
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enddo
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call cft3s (psic_nc(1,1), nr1s, nr2s, nr3s, nrx1s, nrx2s, nrx3s, 2)
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call cft3s (psic_nc(1,2), nr1s, nr2s, nr3s, nrx1s, nrx2s, nrx3s, 2)
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ELSE
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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 cft3s (psic, nr1s, nr2s, nr3s, nrx1s, nrx2s, nrx3s, 2)
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END IF
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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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if (noncolin) then
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if (domag) then
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do j=1, nrxxs
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sup = psic_nc(j,1) * (vrs(j,1)+vrs(j,4)) + &
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psic_nc(j,2) * (vrs(j,2)-(0.d0,1.d0)*vrs(j,3))
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sdwn = psic_nc(j,2) * (vrs(j,1)-vrs(j,4)) + &
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psic_nc(j,1) * (vrs(j,2)+(0.d0,1.d0)*vrs(j,3))
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psic_nc(j,1)=sup
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psic_nc(j,2)=sdwn
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end do
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else
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do j=1, nrxxs
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psic_nc(j,1)=psic_nc(j,1) * vrs(j,1)
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psic_nc(j,2)=psic_nc(j,2) * vrs(j,1)
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enddo
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endif
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else
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do j = 1, nrxxs
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psic (j) = psic (j) * vrs (j, current_spin)
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enddo
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endif
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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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IF (noncolin) THEN
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call cft3s(psic_nc(1,1),nr1s,nr2s,nr3s,nrx1s,nrx2s,nrx3s,-2)
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call cft3s(psic_nc(1,2),nr1s,nr2s,nr3s,nrx1s,nrx2s,nrx3s,-2)
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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_nc (nls(igkq(j)), 1)
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hpsi (j+lda, ibnd) = hpsi (j+lda, ibnd) + psic_nc (nls(igkq(j)), 2)
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enddo
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ELSE
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call cft3s (psic, nr1s, nr2s, nr3s, nrx1s, nrx2s, nrx3s, - 2)
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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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END IF
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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)
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call s_psi (lda, n, m, psi, spsi)
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call stop_clock ('h_psiq')
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return
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end subroutine h_psiq
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