mirror of https://gitlab.com/QEF/q-e.git
171 lines
4.6 KiB
Fortran
171 lines
4.6 KiB
Fortran
!
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! Copyright (C) 2001-2004 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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subroutine add_for_charges (ik, uact)
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!----------===============-----------------------------------------------
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!
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! This subroutine calculates dS/du P_c [x, H-eS] |psi>
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!
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#include "f_defs.h"
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USE ions_base, ONLY : nat, ityp, ntyp => nsp
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use pwcom
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USE kinds, only : DP
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USE uspp_param, only: nh
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use phcom
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implicit none
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!
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! The dummy variables
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!
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integer :: ik, mode
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! input: the k point
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! input: the actual perturbation
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complex(DP) :: uact (3 * nat)
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! input: the pattern of displacements
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!
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! And the local variables
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!
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integer :: na, nb, mu, nu, ikk, ikq, ig, igg, nt, ibnd, ijkb0, &
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ikb, jkb, ih, jh, ipol
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! counter on atoms
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! counter on modes
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! the point k
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! the point k+q
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! counter on G vectors
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! auxiliary counter on G vectors
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! counter on atomic types
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! counter on bands
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! auxiliary variable for counting
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! counter on becp functions
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! counter on becp functions
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! counter on n index
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! counter on m index
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! counter on polarizations
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real(DP), parameter :: eps = 1.d-12
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complex(DP), allocatable :: ps1 (:,:), ps2 (:,:,:), aux (:)
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! the scalar product
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! the scalar product
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! a mesh space for psi
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complex(DP), allocatable :: bedp(:,:), aux1(:,:), alphapp(:,:,:)
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logical :: ok
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! used to save time
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allocate (ps1 ( nkb , nbnd))
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allocate (ps2 ( nkb , nbnd , 3))
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allocate (aux ( npwx))
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allocate (aux1( npwx, npwx))
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allocate (bedp( nkb, nbnd) )
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allocate (alphapp (nkb,nbnd,3))
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if (lgamma) then
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ikk = ik
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ikq = ik
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else
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call infomsg ('add_for_charges', 'called for lgamma .eq. false', -1)
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endif
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if (lsda) current_spin = isk (ikk)
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!
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! we first compute the coefficients of the vectors
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!
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ps1 = (0.d0, 0.d0)
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ps2 = (0.d0, 0.d0)
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aux1 = (0.d0, 0.d0)
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alphapp = (0.d0,0.d0)
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bedp = (0.d0,0.d0)
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!
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! first we calculate the products of the beta functions with dvpsi
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!
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call ccalbec (nkb, npwx, npw, nbnd, bedp, vkb, dpsi)
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do ipol = 1, 3
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do ibnd = 1, nbnd
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do ig = 1, npw
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aux1 (ig, ibnd) = dpsi(ig,ibnd) * &
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tpiba * (0.d0,1.d0) * &
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( xk(ipol,ikk) + g(ipol,igk(ig)) )
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enddo
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enddo
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call ccalbec (nkb, npwx, npw, nbnd, alphapp(1,1,ipol), vkb, aux1)
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enddo
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ijkb0 = 0
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do nt = 1, ntyp
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do na = 1, nat
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if (ityp (na) .eq.nt) then
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mu = 3 * (na - 1)
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if ( abs (uact (mu + 1) ) + &
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abs (uact (mu + 2) ) + &
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abs (uact (mu + 3) ) > eps) then
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do ih = 1, nh (nt)
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ikb = ijkb0 + ih
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do jh = 1, nh (nt)
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jkb = ijkb0 + jh
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do ipol = 1, 3
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do ibnd = 1, nbnd
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ps1 (ikb, ibnd) = ps1 (ikb, ibnd) + &
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qq (ih, jh, nt) * &
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alphapp(jkb, ibnd, ipol) * &
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uact (mu + ipol)
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ps2 (ikb, ibnd, ipol) = ps2 (ikb, ibnd, ipol) + &
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qq (ih, jh, nt) * &
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(0.d0, -1.d0) * &
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bedp (jkb, ibnd) * &
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uact (mu + ipol) * tpiba
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enddo
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enddo
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enddo
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enddo
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endif
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ijkb0 = ijkb0 + nh (nt)
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endif
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enddo
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enddo
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!
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! This term is proportional to beta(k+q+G)
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!
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dvpsi = matmul(vkb,ps1) + dvpsi
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!
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! This term is proportional to (k+q+G)_\alpha*beta(k+q+G)
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!
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do ikb = 1, nkb
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do ipol = 1, 3
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ok = .false.
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do ibnd = 1, nbnd
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ok = ok.or. (abs (ps2 (ikb, ibnd, ipol) ) .gt.eps)
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enddo
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if (ok) then
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do ig = 1, npwq
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igg = igkq (ig)
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aux (ig) = vkb(ig, ikb) * (xk(ipol, ikq) + g(ipol, igg) )
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enddo
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do ibnd = 1, nbnd
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dvpsi(:,ibnd) = ps2(ikb,ibnd,ipol) * aux + dvpsi(:,ibnd)
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enddo
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endif
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enddo
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enddo
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!
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! Now dvpsi contains dS/du x |psi>
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!
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deallocate (aux)
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deallocate (aux1)
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deallocate (ps2)
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deallocate (ps1)
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deallocate (bedp)
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deallocate (alphapp)
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return
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end subroutine add_for_charges
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