mirror of https://gitlab.com/QEF/q-e.git
180 lines
6.2 KiB
Fortran
180 lines
6.2 KiB
Fortran
!
|
|
! Copyright (C) 2001-2012 Quantum ESPRESSO 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 symdynph_gq_new( xq, phi, s, invs, rtau, irt, nsymq, &
|
|
nat, irotmq, minus_q )
|
|
!-----------------------------------------------------------------------
|
|
!! This routine receives as input an unsymmetrized dynamical
|
|
!! matrix expressed on the crystal axes and imposes the symmetry
|
|
!! of the small group of q. Furthermore it imposes also the symmetry
|
|
!! q -> -q+G if present.
|
|
!! February 2020: Update (A. Urru) to include the symmetry operations
|
|
!! that require the time reversal operator (meaning that TS is a
|
|
!! symmetry of the crystal). For more information please see:
|
|
!! Phys. Rev. B 100, 045115 (2019).
|
|
!
|
|
USE kinds, only : DP
|
|
USE constants, ONLY: tpi
|
|
USE symm_base, ONLY : t_rev
|
|
!
|
|
implicit none
|
|
!
|
|
integer :: nat
|
|
!! input: the number of atoms
|
|
integer :: s(3,3,48)
|
|
!! input: the symmetry matrices
|
|
integer :: irt(48,nat)
|
|
!! input: the rotated of each vector
|
|
integer :: invs(48)
|
|
!! input: the inverse of each matrix
|
|
integer :: nsymq
|
|
!! input: the order of the small group
|
|
integer :: irotmq
|
|
!! input: the rotation sending q ->-q+G
|
|
real(DP) :: xq(3)
|
|
!! input: the q point
|
|
real(DP) :: rtau(3,48,nat)
|
|
!! input: the R associated at each t
|
|
logical :: minus_q
|
|
!! input: true if a symmetry q->-q+G
|
|
complex(DP) :: phi(3,3,nat,nat)
|
|
!! inp/out: the matrix to symmetrize
|
|
!
|
|
! ... local variables
|
|
!
|
|
integer :: isymq, sna, snb, irot, na, nb, ipol, jpol, lpol, kpol, &
|
|
iflb (nat, nat)
|
|
! counters, indices, work space
|
|
|
|
real(DP) :: arg
|
|
! the argument of the phase
|
|
|
|
complex(DP) :: phip (3, 3, nat, nat), work (3, 3), fase, faseq (48)
|
|
! work space, phase factors
|
|
!
|
|
! We start by imposing hermiticity
|
|
!
|
|
do na = 1, nat
|
|
do nb = 1, nat
|
|
do ipol = 1, 3
|
|
do jpol = 1, 3
|
|
phi (ipol, jpol, na, nb) = 0.5d0 * (phi (ipol, jpol, na, nb) &
|
|
+ CONJG(phi (jpol, ipol, nb, na) ) )
|
|
phi (jpol, ipol, nb, na) = CONJG(phi (ipol, jpol, na, nb) )
|
|
enddo
|
|
enddo
|
|
enddo
|
|
enddo
|
|
!
|
|
! If no other symmetry is present we quit here
|
|
!
|
|
if ( (nsymq == 1) .and. (.not.minus_q) ) return
|
|
!
|
|
! Then we impose the symmetry q -> -q+G if present
|
|
!
|
|
if (minus_q) then
|
|
do na = 1, nat
|
|
do nb = 1, nat
|
|
do ipol = 1, 3
|
|
do jpol = 1, 3
|
|
work(:,:) = (0.d0, 0.d0)
|
|
sna = irt (irotmq, na)
|
|
snb = irt (irotmq, nb)
|
|
arg = 0.d0
|
|
do kpol = 1, 3
|
|
arg = arg + (xq (kpol) * (rtau (kpol, irotmq, na) - &
|
|
rtau (kpol, irotmq, nb) ) )
|
|
enddo
|
|
arg = arg * tpi
|
|
fase = CMPLX(cos (arg), sin (arg) ,kind=DP)
|
|
do kpol = 1, 3
|
|
do lpol = 1, 3
|
|
work (ipol, jpol) = work (ipol, jpol) + &
|
|
s (ipol, kpol, irotmq) * s (jpol, lpol, irotmq) &
|
|
* phi (kpol, lpol, sna, snb) * fase
|
|
enddo
|
|
enddo
|
|
phip (ipol, jpol, na, nb) = (phi (ipol, jpol, na, nb) + &
|
|
CONJG( work (ipol, jpol) ) ) * 0.5d0
|
|
enddo
|
|
enddo
|
|
enddo
|
|
enddo
|
|
phi = phip
|
|
endif
|
|
|
|
!
|
|
! Here we symmetrize with respect to the small group of q
|
|
!
|
|
if (nsymq == 1) return
|
|
|
|
iflb (:, :) = 0
|
|
do na = 1, nat
|
|
do nb = 1, nat
|
|
if (iflb (na, nb) == 0) then
|
|
work(:,:) = (0.d0, 0.d0)
|
|
do isymq = 1, nsymq
|
|
irot = isymq
|
|
sna = irt (irot, na)
|
|
snb = irt (irot, nb)
|
|
arg = 0.d0
|
|
do ipol = 1, 3
|
|
arg = arg + (xq (ipol) * (rtau (ipol, irot, na) - &
|
|
rtau (ipol, irot, nb) ) )
|
|
enddo
|
|
arg = arg * tpi
|
|
faseq (isymq) = CMPLX(cos (arg), sin (arg) ,kind=DP)
|
|
do ipol = 1, 3
|
|
do jpol = 1, 3
|
|
do kpol = 1, 3
|
|
do lpol = 1, 3
|
|
IF (t_rev(isymq)==1) THEN
|
|
work (ipol, jpol) = work (ipol, jpol) + &
|
|
s (ipol, kpol, irot) * s (jpol, lpol, irot) &
|
|
* CONJG(phi (kpol, lpol, sna, snb) * faseq (isymq))
|
|
ELSE
|
|
work (ipol, jpol) = work (ipol, jpol) + &
|
|
s (ipol, kpol, irot) * s (jpol, lpol, irot) &
|
|
* phi (kpol, lpol, sna, snb) * faseq (isymq)
|
|
ENDIF
|
|
enddo
|
|
enddo
|
|
enddo
|
|
enddo
|
|
enddo
|
|
do isymq = 1, nsymq
|
|
irot = isymq
|
|
sna = irt (irot, na)
|
|
snb = irt (irot, nb)
|
|
do ipol = 1, 3
|
|
do jpol = 1, 3
|
|
phi (ipol, jpol, sna, snb) = (0.d0, 0.d0)
|
|
do kpol = 1, 3
|
|
do lpol = 1, 3
|
|
IF (t_rev(isymq)==1) THEN
|
|
phi(ipol,jpol,sna,snb)=phi(ipol,jpol,sna,snb) &
|
|
+ s(ipol,kpol,invs(irot))*s(jpol,lpol,invs(irot))&
|
|
* CONJG(work (kpol, lpol)*faseq (isymq))
|
|
ELSE
|
|
phi(ipol,jpol,sna,snb)=phi(ipol,jpol,sna,snb) &
|
|
+ s(ipol,kpol,invs(irot))*s(jpol,lpol,invs(irot))&
|
|
* work (kpol, lpol) * CONJG(faseq (isymq) )
|
|
ENDIF
|
|
enddo
|
|
enddo
|
|
enddo
|
|
enddo
|
|
iflb (sna, snb) = 1
|
|
enddo
|
|
endif
|
|
enddo
|
|
enddo
|
|
phi (:, :, :, :) = phi (:, :, :, :) / DBLE(nsymq)
|
|
return
|
|
end subroutine symdynph_gq_new
|