mirror of https://gitlab.com/QEF/q-e.git
80 lines
2.1 KiB
Fortran
80 lines
2.1 KiB
Fortran
!
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! Copyright (C) 2001-2003 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 compute_weight (wgg)
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!-----------------------------------------------------------------------
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!
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! This routine implements Eq.15 (B) of the notes. It computes the
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! weight to give to the v,v' terms in the orthogonality term
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!
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use pwcom
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use parameters, only : DP
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use phcom
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implicit none
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real(kind=DP) :: wgg (nbnd, nbnd, nksq)
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! output: the weights
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integer :: ik, ikk, ikq, ibnd, jbnd
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! counters
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real(kind=DP) :: wg1, wg2, theta
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! auxiliary variables
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real(kind=DP), external :: wgauss
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real(kind=DP), parameter :: eps = 1.0d-12
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!
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! the weights are computed for each k point ...
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!
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do ik = 1, nksq
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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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ikk = 2 * ik - 1
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ikq = ikk + 1
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endif
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!
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! each band v ...
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!
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do ibnd = 1, nbnd
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if (wk (ikk) .eq.0.d0) then
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wg1 = 0.d0
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else
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wg1 = wg (ibnd, ikk) / wk (ikk)
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endif
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!
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! and each band v' ...
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!
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do jbnd = 1, nbnd
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if (degauss.ne.0.d0) then
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theta = wgauss ( (et (jbnd,ikq) - et (ibnd,ikk) ) / degauss, 0)
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wg2 = wgauss ( (ef - et (jbnd, ikq) ) / degauss, ngauss)
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else
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theta = 0.5d0
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if (wk (ikk) .le.eps) then
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wg2 = 0.d0
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else
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wg2 = wg (jbnd, ikk) / wk (ikk)
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endif
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endif
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wgg (ibnd, jbnd, ik) = wg1 * (1.d0 - theta) + wg2 * theta
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enddo
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enddo
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! do ibnd=1,nbnd
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! do jbnd=1,nbnd
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! WRITE( stdout,'(3i5,f20.10)') ibnd, jbnd, ik,wgg(ibnd,jbnd,ik)
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! enddo
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! enddo
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enddo
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! call stop_ph(.true.)
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return
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end subroutine compute_weight
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