mirror of https://gitlab.com/QEF/q-e.git
44 lines
1.4 KiB
Fortran
44 lines
1.4 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 gweights (nks, wk, nbnd, nelec, degauss, ngauss, &
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et, ef, demet, wg)
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!--------------------------------------------------------------------
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! calculates weights with the gaussian spreading technique
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use parameters
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implicit none
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!
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integer :: nks, nbnd, ngauss
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real(kind=DP) :: wk (nks), et (nbnd, nks), nelec, degauss
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real(kind=DP) :: wg (nbnd, nks), ef, demet
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!
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integer :: kpoint, ibnd
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real(kind=DP) , external :: wgauss, w1gauss
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! Calculate the Fermi energy ef
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call efermig (et, nbnd, nks, nelec, wk, degauss, ngauss, ef)
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demet = 0.d0
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do kpoint = 1, nks
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do ibnd = 1, nbnd
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! Calculate the gaussian weights
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wg (ibnd, kpoint) = wk (kpoint) * wgauss ( (ef - et (ibnd, kpoint) &
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) / degauss, ngauss)
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! The correct form of the band energy is \int e n(e) de for e<ef
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! demet is the correction to add to the sum of eigenvalues
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demet = demet + wk (kpoint) * degauss * w1gauss ( (ef - et (ibnd, &
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kpoint) ) / degauss, ngauss)
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enddo
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enddo
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return
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end subroutine gweights
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