mirror of https://gitlab.com/QEF/q-e.git
120 lines
3.3 KiB
Fortran
120 lines
3.3 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 symm(phi, u, xq, s, isym, rtau, irt, at, bg, nat)
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!-----------------------------------------------------------------------
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!
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! This routine symmetrizes the matrix of electron-phonon coefficients
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! written in the basis of the modes
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!
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USE kinds, ONLY: DP
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USE constants, ONLY: tpi
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!
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implicit none
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integer, intent (in) :: nat, s (3,3,48), irt (48, nat), isym
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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 atom
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! input: the small group of q
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real(DP), intent (in) :: xq (3), rtau (3, 48, nat), at (3, 3), bg (3, 3)
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! input: the coordinates of q
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! input: the R associated at each r
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! input: direct lattice vectors
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! input: reciprocal lattice vectors
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complex(DP), intent(in) :: u(3*nat,3*nat)
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! input: patterns
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complex(DP), intent(inout) :: phi(3*nat,3*nat)
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! input: matrix to be symmetrized , output: symmetrized matrix
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integer :: i, j, icart, jcart, na, nb, mu, nu, sna, snb, &
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ipol, jpol, lpol, kpol
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! counters
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real(DP) :: arg
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!
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complex(DP) :: fase, work, wrk(3,3), phi1(3,3,nat,nat), phi2(3,3,nat,nat)
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! workspace
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!
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! First we transform to cartesian coordinates
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!
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do i = 1, 3 * nat
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na = (i - 1) / 3 + 1
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icart = i - 3 * (na - 1)
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do j = 1, 3 * nat
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nb = (j - 1) / 3 + 1
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jcart = j - 3 * (nb - 1)
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work = (0.d0, 0.d0)
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do mu = 1, 3 * nat
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do nu = 1, 3 * nat
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work = work + u(i,mu) * phi(mu,nu) * conjg(u(j,nu))
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enddo
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enddo
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phi1(icart,jcart,na,nb) = work
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enddo
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enddo
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!
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! Then we transform to crystal axis
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!
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do na = 1, nat
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do nb = 1, nat
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call trntnsc (phi1(1,1,na,nb), at, bg, - 1)
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enddo
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enddo
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!
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! And we symmetrize in this basis
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!
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do na = 1, nat
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do nb = 1, nat
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sna = irt (isym, na)
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snb = irt (isym, 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,isym,na) - rtau(ipol,isym,nb)))
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enddo
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arg = arg * tpi
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fase = DCMPLX (cos (arg), sin (arg) )
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do ipol = 1, 3
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do jpol = 1, 3
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phi2(ipol,jpol,na,nb) = (0.0d0,0.0d0)
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do kpol = 1, 3
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do lpol = 1, 3
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phi2(ipol,jpol,na,nb) = phi2(ipol,jpol,na,nb) + &
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s(ipol,kpol,isym) * s(jpol,lpol,isym) * &
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phi1(kpol,lpol,sna,snb) * fase
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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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! Back to cartesian coordinates
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!
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do na = 1, nat
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do nb = 1, nat
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call trntnsc (phi2 (1, 1, na, nb), at, bg, + 1)
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enddo
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enddo
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!
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! rewrite as an array with dimensions 3nat x 3nat
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!
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do i = 1, 3 * nat
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na = (i - 1) / 3 + 1
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icart = i - 3 * (na - 1)
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do j = 1, 3 * nat
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nb = (j - 1) / 3 + 1
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jcart = j - 3 * (nb - 1)
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phi (i, j) = phi2 (icart, jcart, na, nb)
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enddo
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enddo
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!
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return
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end subroutine symm
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