mirror of https://gitlab.com/QEF/q-e.git
71 lines
1.9 KiB
Fortran
71 lines
1.9 KiB
Fortran
!
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! Copyright (C) 2001 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 stres_har (sigmahar)
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!----------------------------------------------------------------------
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!
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#include "machine.h"
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USE kinds, ONLY : DP
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USE constants, ONLY : e2, fpi
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USE cell_base, ONLY: omega, tpiba2
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USE ener, ONLY: ehart
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USE gvect, ONLY: ngm, gstart, nr1, nr2, nr3, nrx1, nrx2, nrx3, &
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nrxx , nl, g, gg
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USE lsda_mod, ONLY: nspin
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USE scf, ONLY: rho
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USE wvfct, ONLY: gamma_only
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USE wavefunctions_module, ONLY : psic
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implicit none
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!
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real(kind=DP) :: sigmahar (3, 3), shart, g2
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real(kind=DP), parameter :: eps = 1.d-8
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integer :: is, ig, igl0, l, m
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sigmahar(:,:) = 0.d0
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psic (:) = (0.d0, 0.d0)
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do is = 1, nspin
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call DAXPY (nrxx, 1.d0, rho (1, is), 1, psic, 2)
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enddo
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call cft3 (psic, nr1, nr2, nr3, nrx1, nrx2, nrx3, - 1)
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! psic contains now the charge density in G space
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! the G=0 component is not computed
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do ig = gstart, ngm
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g2 = gg (ig) * tpiba2
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shart = psic (nl (ig) ) * conjg (psic (nl (ig) ) ) / g2
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do l = 1, 3
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do m = 1, l
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sigmahar (l, m) = sigmahar (l, m) + shart * tpiba2 * 2 * &
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g (l, ig) * g (m, ig) / g2
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enddo
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enddo
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enddo
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#ifdef __PARA
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call reduce (9, sigmahar)
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#endif
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if (gamma_only) then
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sigmahar(:,:) = fpi * e2 * sigmahar(:,:)
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else
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sigmahar(:,:) = 0.5 * fpi * e2 * sigmahar(:,:)
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end if
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do l = 1, 3
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sigmahar (l, l) = sigmahar (l, l) - ehart / omega
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enddo
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do l = 1, 3
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do m = 1, l - 1
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sigmahar (m, l) = sigmahar (l, m)
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enddo
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enddo
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sigmahar(:,:) = -sigmahar(:,:)
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return
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end subroutine stres_har
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