quantum-espresso/D3/qstar_d3.f90

127 lines
3.5 KiB
Fortran

!
! Copyright (C) 2001 PWSCF group
! This file is distributed under the terms of the
! GNU General Public License. See the file `License'
! in the root directory of the present distribution,
! or http://www.gnu.org/copyleft/gpl.txt .
!
!-----------------------------------------------------------------------
subroutine qstar_d3 (d3dyn, at, bg, nat, nsym, s, invs, irt, rtau, &
nq, sxq, isq, imq, iudyn, wrmode)
!-----------------------------------------------------------------------
!
USE kinds, only : DP
implicit none
!
! input variables
!
integer :: nat, nsym, s (3, 3, 48), invs (48), irt (48, nat), &
nq, isq (48), imq, iudyn
! number of atoms in the unit cell
! number of symmetry operations
! the symmetry operations
! index of the inverse operations
! index of the rotated atom
! degeneracy of the star of q
! symmetry op. giving the rotated q
! index of -q in the star (0 if nont present)
! unit number
complex (DP) :: d3dyn (3 * nat, 3 * nat, 3 * nat)
! the dynmatrix derivative
real (DP) :: at (3, 3), bg (3, 3), rtau (3, 48, nat), sxq (3, 48)
! direct lattice vectors
! reciprocal lattice vectors
! position of rotated atoms for each sym.op.
! list of q in the star
logical :: wrmode (3 * nat )
! if .true. this mode is to be written
!
! local variables
!
integer :: iq, nsq, isym, na, nb, nc, icar, jcar, kcar, i, j, k
! counters
complex (DP), allocatable :: phi (:,:,:,:,:,:), phi2 (:,:,:,:,:,:)
! work space
allocate (phi (3,3,3,nat,nat,nat))
allocate (phi2(3,3,3,nat,nat,nat))
!
! Sets number of symmetry operations giving each q in the list
!
nsq = nsym / nq
if (nsq * nq /= nsym) call errore ('qstar_d3', 'wrong degeneracy', 1)
!
! Writes dyn.mat d3dyn(3*nat,3*nat,3*nat)
! on the 6-index array phi(3,3,3,nat,nat,nat)
!
do i = 1, 3 * nat
na = (i - 1) / 3 + 1
icar = i - 3 * (na - 1)
do j = 1, 3 * nat
nb = (j - 1) / 3 + 1
jcar = j - 3 * (nb - 1)
do k = 1, 3 * nat
nc = (k - 1) / 3 + 1
kcar = k - 3 * (nc - 1)
phi (icar, jcar, kcar, na, nb, nc) = d3dyn (i, j, k)
enddo
enddo
enddo
!
! Goes to crystal coordinates
!
do na = 1, nat
do nb = 1, nat
do nc = 1, nat
call trntnsc_3 (phi (1, 1, 1, na, nb, nc), at, bg, - 1)
enddo
enddo
enddo
!
! For each q of the star rotates phi with the appropriate sym.op. -> phi
!
do iq = 1, nq
phi2 (:,:,:,:,:,:) = (0.d0, 0.d0)
do isym = 1, nsym
if (isq (isym) == iq) then
call rotate_and_add_d3 (phi, phi2, nat, isym, s, invs, irt, &
rtau, sxq (1, iq) )
endif
enddo
phi2 = phi2 / DBLE (nsq)
!
! Back to cartesian coordinates
!
do na = 1, nat
do nb = 1, nat
do nc = 1, nat
call trntnsc_3 (phi2 (1, 1, 1, na, nb, nc), at, bg, + 1)
enddo
enddo
enddo
!
! Writes the dynamical matrix in cartesian coordinates on file
!
call write_d3dyn (sxq (1, iq), phi2, nat, iudyn, wrmode)
if (imq == 0) then
!
! if -q is not in the star recovers its matrix by time reversal
!
phi2 (:,:,:,:,:,:) = CONJG(phi2 (:,:,:,:,:,:) )
!
! and writes it (changing temporarily sign to q)
!
sxq (:, iq) = - sxq (:, iq)
call write_d3dyn (sxq (1, iq), phi2, nat, iudyn, wrmode)
sxq (:, iq) = - sxq (:, iq)
endif
enddo
deallocate (phi)
deallocate (phi2)
return
end subroutine qstar_d3