mirror of https://gitlab.com/QEF/q-e.git
51 lines
1.9 KiB
Fortran
51 lines
1.9 KiB
Fortran
!
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! Copyright (C) 2002 FPMD 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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MODULE cp_electronic_mass
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!------------------------------------------------------------------------------!
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! This module contains variable and functions relative to the
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! Car-Parrinello fictitious electronic masse
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USE kinds, ONLY: dbl
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!
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IMPLICIT NONE
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SAVE
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REAL(dbl) :: emass = 1.0d0 ! fictitious electronic mass ( mu )
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REAL(dbl) :: emass_cutoff = 1.0d0 ! kinetic energy cutoff for plane
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! waves to be used for Fourier acceleration
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! preconditioning
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!------------------------------------------------------------------------------!
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CONTAINS
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!------------------------------------------------------------------------------!
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SUBROUTINE emass_precond( ema0bg, ggp, ngw, tpiba2, emaec )
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USE control_flags, ONLY: iprsta
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IMPLICIT NONE
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REAL(dbl), INTENT(OUT) :: ema0bg(:)
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REAL(dbl), INTENT(IN) :: ggp(:), tpiba2, emaec
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INTEGER, INTENT(IN) :: ngw
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INTEGER :: i
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! mass preconditioning: ema0bg(i) = ratio of emass(g=0) to emass(g)
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! for g**2>emaec the electron mass ema0bg(g) rises quadratically
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do i = 1, ngw
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ema0bg(i) = 1.0d0 / MAX( 1.d0, tpiba2 * ggp(i) / emaec )
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IF( iprsta >= 10 ) print *,i,' ema0bg(i) ',ema0bg(i)
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end do
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RETURN
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END SUBROUTINE
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!------------------------------------------------------------------------------!
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END MODULE cp_electronic_mass
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!------------------------------------------------------------------------------!
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