mirror of https://gitlab.com/QEF/q-e.git
76 lines
2.3 KiB
Fortran
76 lines
2.3 KiB
Fortran
!
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! Copyright (C) 2001-2008 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 compute_dvloc (mode, dvlocin)
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!----------------------------------------------------------------------
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!
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! This routine calculates dV_bare/dtau * psi for one perturbation
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! with a given q. The displacements are described by a vector u.
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! The result is stored in dvpsi. The routine is called for each k point
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! and for each pattern u. It computes simultaneously all the bands.
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!
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#include "f_defs.h"
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!
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USE kinds, ONLY : DP
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USE gvect, ONLY : eigts1, eigts2, eigts3, ig1,ig2,ig3, g
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USE gsmooth, ONLY : nrxxs, ngms, nr1s,nr2s,nr3s, nrx1s,nrx2s,nrx3s, nls
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USE cell_base, ONLY : tpiba
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USE ions_base, ONLY : nat, ityp
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USE modes, ONLY : u
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USE qpoint, ONLY : xq, eigqts
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USE eqv, ONLY : evq, vlocq
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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 :: mode
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! input: the actual perturbation
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complex(DP) :: dvlocin (nrxxs)
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! output: the change of the local potential
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!
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! And the local variables
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!
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integer :: na, nt, mu, ig
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! counters
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complex(DP) :: gtau, gu, fact, u1, u2, u3, gu0
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! auxiliary variables
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call start_clock ('com_dvloc')
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dvlocin (:) = (0.d0, 0.d0)
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do na = 1, nat
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fact = tpiba * (0.d0, -1.d0) * eigqts (na)
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mu = 3 * (na - 1)
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if ( abs (u (mu + 1, mode) ) + abs (u (mu + 2, mode) ) + &
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abs (u (mu + 3, mode) ) > 1.0d-12) then
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nt = ityp (na)
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u1 = u (mu + 1, mode)
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u2 = u (mu + 2, mode)
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u3 = u (mu + 3, mode)
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gu0 = xq (1) * u1 + xq (2) * u2 + xq (3) * u3
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do ig = 1, ngms
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gtau = eigts1 (ig1 (ig), na) * eigts2 (ig2 (ig), na) * eigts3 ( &
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ig3 (ig), na)
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gu = gu0 + g (1, ig) * u1 + g (2, ig) * u2 + g (3, ig) * u3
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dvlocin (nls (ig) ) = dvlocin (nls (ig) ) + vlocq (ig, nt) &
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* gu * fact * gtau
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enddo
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endif
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enddo
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!
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! Now we compute dV_loc/dtau in real space
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!
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call cft3s (dvlocin, nr1s, nr2s, nr3s, nrx1s, nrx2s, nrx3s, + 1)
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call stop_clock ('com_dvloc')
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return
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end subroutine compute_dvloc
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