mirror of https://gitlab.com/QEF/q-e.git
78 lines
1.9 KiB
Fortran
78 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 trntnsr_3 (phi, at, bg, iflg)
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!-----------------------------------------------------------------------
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!
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! trasforms a REAL third order tensor
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! from crystal to cartesian axis (iflg >= 1) or viceversa (iflg <= -1)
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!
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#include "f_defs.h"
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use kinds, only : DP
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implicit none
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integer :: iflg
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! input: gives the versus of the trans.
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real(DP) :: phi (3, 3, 3), at (3, 3), bg (3, 3)
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! inp/out: the matrix to transform
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! input: the direct lattice vectors
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! input: the reciprocal lattice
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integer :: i, j, k, l, m, n
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! counters on polarizations
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real(DP) :: wrk (3, 3, 3)
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! a working array
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if(iflg.gt.0) then
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!
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! forward transformation (crystal to cartesian axis)
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!
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call DCOPY(27, phi, 1, wrk, 1)
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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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phi (i, j, k) = 0.d0
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do l = 1, 3
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do m = 1, 3
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do n = 1, 3
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phi (i, j, k) = phi (i, j, k) + &
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wrk (l, m, n) * bg (i, l) * bg (j, m) * bg (k, n)
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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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enddo
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else
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!
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! backward transformation (cartesian to crystal axis)
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!
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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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wrk (i,j,k) = 0.d0
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do l = 1, 3
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do m = 1, 3
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do n = 1, 3
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wrk (i, j, k) = wrk (i, j, k) + &
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phi (l, m, n) * at (l, i) * at (m, j) * at (n, k)
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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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enddo
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call DCOPY (27, wrk, 1, phi, 1)
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endif
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return
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end subroutine trntnsr_3
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