mirror of https://gitlab.com/QEF/q-e.git
45 lines
954 B
Fortran
45 lines
954 B
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 symtns (phi, nsym, s)
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!-----------------------------------------------------------------------
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!
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! symmetrize a tensor in the basis of crystallographic axis
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!
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#include "f_defs.h"
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USE kinds
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implicit none
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integer :: nsym, s (3, 3, 48), isym, i, j, k, l
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real(DP) :: phi (3, 3), work (3, 3)
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external DSCAL, DCOPY
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!
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if (nsym.eq.1) return
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work(:,:) = 0.d0
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!
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do isym = 1, nsym
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do i = 1, 3
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do j = 1, 3
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do k = 1, 3
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do l = 1, 3
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work (i, j) = work (i, j) + s (i, k, isym) * s (j, l, isym) &
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* phi (k, l)
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enddo
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enddo
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enddo
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enddo
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enddo
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!
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call DSCAL (9, 1.d0 / nsym, work, 1)
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call DCOPY (9, work, 1, phi, 1)
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!
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return
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end subroutine symtns
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