mirror of https://gitlab.com/QEF/q-e.git
51 lines
1.4 KiB
Fortran
51 lines
1.4 KiB
Fortran
!
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! Copyright (C) 2007 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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#include "f_defs.h"
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!
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!----------------------------------------------------------------------------
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SUBROUTINE g2_kin ( ik )
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!----------------------------------------------------------------------------
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!
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! ... Calculation of kinetic energy - includes the case of the modified
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! ... kinetic energy functional for variable-cell calculations
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!
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USE kinds, ONLY : DP
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USE cell_base, ONLY : tpiba2
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USE klist, ONLY : xk
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USE gvect, ONLY : g, ecfixed, qcutz, q2sigma
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USE wvfct, ONLY : g2kin, igk, npw
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!
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IMPLICIT NONE
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!
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INTEGER, INTENT (IN) :: ik
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!
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! ... local variables
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!
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INTEGER :: ig
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REAL(DP), EXTERNAL :: erf
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!
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!
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g2kin(1:npw) = ( ( xk(1,ik) + g(1,igk(1:npw)) )**2 + &
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( xk(2,ik) + g(2,igk(1:npw)) )**2 + &
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( xk(3,ik) + g(3,igk(1:npw)) )**2 ) * tpiba2
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!
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IF ( qcutz > 0.D0 ) THEN
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!
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DO ig = 1, npw
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!
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g2kin(ig) = g2kin(ig) + qcutz * &
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( 1.D0 + erf( ( g2kin(ig) - ecfixed ) / q2sigma ) )
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!
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END DO
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!
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END IF
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!
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RETURN
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!
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END SUBROUTINE g2_kin
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