mirror of https://gitlab.com/QEF/q-e.git
218 lines
7.4 KiB
Fortran
218 lines
7.4 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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subroutine d3_symdynph (xq, phi, s, invs, rtau, irt, irgq, nsymq, &
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nat, irotmq, minus_q)
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!-----------------------------------------------------------------------
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!
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! This routine receives as input an unsymmetrized dynamical
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! matrix expressed on the crystal axes and imposes the symmetry
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! of the small group of q. Furthermore it imposes also the symmetry
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! q -> -q+G if present.
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!
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!
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USE kinds, only : DP
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USE constants, only : tpi
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implicit none
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!
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! The dummy variables
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!
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integer :: nat, s (3, 3, 48), irt (48, nat), irgq (48), invs (48), &
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nsymq, irotmq
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! input: the number of atoms
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! input: the symmetry matrices
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! input: the rotated of each vector
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! input: the small group of q
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! input: the inverse of each matrix
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! input: the order of the small gro
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! input: the rotation sending q ->
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real (DP) :: xq (3), rtau (3, 48, nat)
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! input: the q point
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! input: the R associated at each t
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logical :: minus_q
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! input: true if a symmetry q->-q+G
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complex (DP) :: phi (3, 3, 3, nat, nat, nat)
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! inp/out: the matrix to symmetrize
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!
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! local variables
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!
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integer :: isymq, sna, snb, snc, irot, na, nb, nc, ipol, jpol, &
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lpol, kpol, mpol, npol
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! counters
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integer, allocatable:: iflb (:,:,:)
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! used to account for symmetrized elements
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real (DP) :: arg
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! the argument of the phase
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complex (DP), allocatable :: phip (:,:,:,:,:,:)
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! work space
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complex (DP) :: work (3, 3, 3), fase, faseq (48)
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! the phase factor
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! the phases for each symmetry
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!
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! We start by imposing hermiticity
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!
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do nc = 1, nat
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do na = 1, nat
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do nb = 1, nat
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do kpol = 1, 3
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do ipol = 1, 3
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do jpol = 1, 3
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phi (kpol, ipol, jpol, nc, na, nb) = 0.5d0 * &
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(phi (kpol, ipol, jpol, nc, na, nb) + &
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CONJG(phi (kpol, jpol, ipol, nc, nb, na) ) )
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phi (kpol, jpol, ipol, nc, nb, na) = &
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CONJG(phi (kpol, ipol, jpol, nc, na, nb) )
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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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!
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! If no other symmetry is present we quit here
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!
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if ( (nsymq == 1) .and. (.not.minus_q) ) return
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allocate (phip( 3, 3, 3, nat, nat, nat))
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!
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! Then we impose the symmetry q -> -q+G if present
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!
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if (minus_q) then
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do nc = 1, nat
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do na = 1, nat
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do nb = 1, nat
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do mpol = 1, 3
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do ipol = 1, 3
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do jpol = 1, 3
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work = (0.d0, 0.d0)
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snc = irt (irotmq, nc)
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sna = irt (irotmq, na)
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snb = irt (irotmq, nb)
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arg = 0.d0
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do kpol = 1, 3
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arg = arg + (xq (kpol) * (rtau (kpol, irotmq, na) - &
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rtau (kpol, irotmq, nb) ) )
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enddo
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arg = arg * tpi
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fase = CMPLX(cos (arg), sin (arg) ,kind=DP)
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do npol = 1, 3
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do kpol = 1, 3
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do lpol = 1, 3
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work (mpol, ipol, jpol) = work (mpol, ipol, jpol) + &
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fase * s (ipol, kpol, irotmq) * &
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s (jpol, lpol, irotmq) * &
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s (mpol, npol, irotmq) * &
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phi (npol, kpol, lpol, snc, sna, snb)
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enddo
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enddo
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enddo
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phip (mpol, ipol, jpol, nc, na, nb) = &
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(phi (mpol, ipol, jpol, nc, na, nb) + &
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CONJG(work (mpol, ipol, jpol) ) ) * 0.5d0
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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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phi = phip
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endif
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deallocate (phip)
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!
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! Here we symmetrize with respect to the small group of q
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!
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if (nsymq == 1) return
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allocate (iflb( nat, nat, nat))
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do na = 1, nat
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do nb = 1, nat
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do nc = 1, nat
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iflb (nc, na, nb) = 0
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enddo
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enddo
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enddo
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do nc = 1, nat
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do na = 1, nat
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do nb = 1, nat
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if (iflb (nc, na, nb) .eq.0) then
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work = (0.d0, 0.d0)
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do isymq = 1, nsymq
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irot = irgq (isymq)
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snc = irt (irot, nc)
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sna = irt (irot, na)
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snb = irt (irot, nb)
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arg = 0.d0
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do ipol = 1, 3
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arg = arg + (xq (ipol) * (rtau (ipol, irot, na) - &
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rtau (ipol, irot, nb) ) )
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enddo
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arg = arg * tpi
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faseq (isymq) = CMPLX(cos (arg), sin (arg) ,kind=DP)
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do mpol = 1, 3
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do ipol = 1, 3
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do jpol = 1, 3
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do npol = 1, 3
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do kpol = 1, 3
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do lpol = 1, 3
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work (mpol, ipol, jpol) = work (mpol, ipol, jpol) + &
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s (ipol, kpol, irot) * &
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s (jpol, lpol, irot) * &
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s (mpol, npol, irot) * &
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phi (npol, kpol, lpol, snc, sna, snb) &
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* faseq (isymq)
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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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enddo
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do isymq = 1, nsymq
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irot = irgq (isymq)
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snc = irt (irot, nc)
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sna = irt (irot, na)
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snb = irt (irot, nb)
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do mpol = 1, 3
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do ipol = 1, 3
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do jpol = 1, 3
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phi (mpol, ipol, jpol, snc, sna, snb) = (0.d0, 0.d0)
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do npol = 1, 3
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do kpol = 1, 3
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do lpol = 1, 3
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phi (mpol, ipol, jpol, snc, sna, snb) = &
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phi (mpol, ipol, jpol, snc, sna, snb) +&
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s (mpol, npol, invs (irot) ) * &
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s (ipol, kpol, invs (irot) ) * &
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s (jpol, lpol, invs (irot) ) * &
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work (npol, kpol, lpol) * &
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CONJG(faseq (isymq) )
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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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iflb (snc, sna, snb) = 1
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enddo
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endif
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enddo
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enddo
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enddo
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phi = phi / DBLE(nsymq)
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deallocate (iflb)
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return
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end subroutine d3_symdynph
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