mirror of https://gitlab.com/QEF/q-e.git
162 lines
4.8 KiB
Fortran
162 lines
4.8 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 dqvan2 (ngy, ih, jh, np, qmod, dqg, ylmk0, dylmk0, ipol)
|
|
!-----------------------------------------------------------------------
|
|
!
|
|
! This routine computes the derivatives of the fourier transform of
|
|
! the Q function needed in stress assuming that the radial fourier
|
|
! trasform is already computed and stored in table qrad.
|
|
!
|
|
! The formula implemented here is
|
|
!
|
|
! dq(g,l,k) = sum_lm (-i)^l ap(lm,l,k) *
|
|
! ( yr_lm(g^) dqrad(g,l,l,k) + dyr_lm(g^) qrad(g,l,l,k))
|
|
!
|
|
! here the dummy variables
|
|
!
|
|
USE kinds, ONLY: DP
|
|
USE gvect, ONLY: g
|
|
USE us, ONLY: dq, qrad
|
|
USE uspp_param, ONLY: lmaxq, nbetam
|
|
USE uspp, ONLY: nlx, lpl, lpx, ap, indv, nhtol, nhtolm
|
|
implicit none
|
|
integer :: ngy, ih, jh, np, ipol
|
|
! input: the number of G vectors to compute
|
|
! input: the first index of Q
|
|
! input: the second index of Q
|
|
! input: the number of the pseudopotential
|
|
! input: the polarization of the derivative
|
|
|
|
real(DP) :: ylmk0 (ngy, lmaxq * lmaxq), dylmk0 (ngy, lmaxq * lmaxq), &
|
|
qmod (ngy)
|
|
! the spherical harmonics
|
|
! the spherical harmonics derivetives
|
|
! input: moduli of the q+g vectors
|
|
complex(DP) :: dqg (ngy)
|
|
! output: the fourier transform of interest
|
|
!
|
|
! here the local variables
|
|
!
|
|
|
|
complex(DP) :: sig
|
|
! (-i)^L
|
|
|
|
integer :: nb, mb, ijv, ivl, jvl, ig, lp, l, lm, i0, i1, i2, i3
|
|
! the atomic index corresponding to ih
|
|
! the atomic index corresponding to jh
|
|
! combined index (nb,mb)
|
|
! the lm corresponding to ih
|
|
! the lm corresponding to jh
|
|
! counter on g vectors
|
|
! the actual LM
|
|
! the angular momentum L
|
|
! the possible LM's compatible with ih,j
|
|
! counters for interpolation table
|
|
|
|
real(DP) :: sixth, dqi, qm, px, ux, vx, wx, uvx, pwx, work, work1, qm1
|
|
! 1 divided by six
|
|
! 1 divided dq
|
|
! qmod/dq
|
|
! measures for interpolation table
|
|
! auxiliary variables for intepolation
|
|
! auxiliary variable
|
|
! auxiliary variable
|
|
!
|
|
! compute the indices which correspond to ih,jh
|
|
!
|
|
sixth = 1.d0 / 6.d0
|
|
dqi = 1 / dq
|
|
nb = indv (ih, np)
|
|
mb = indv (jh, np)
|
|
if (nb.ge.mb) then
|
|
ijv = nb * (nb - 1) / 2 + mb
|
|
else
|
|
ijv = mb * (mb - 1) / 2 + nb
|
|
endif
|
|
ivl = nhtolm (ih, np)
|
|
jvl = nhtolm (jh, np)
|
|
|
|
if (nb > nbetam .OR. mb > nbetam) &
|
|
call errore (' dqvan2 ', ' wrong dimensions (1)', MAX(nb,mb))
|
|
if (ivl > nlx .OR. jvl > nlx) &
|
|
call errore (' dqvan2 ', ' wrong dimensions (2)', MAX(ivl,jvl))
|
|
|
|
dqg(:) = (0.d0,0.d0)
|
|
!
|
|
! and make the sum over the non zero LM
|
|
!
|
|
do lm = 1, lpx (ivl, jvl)
|
|
lp = lpl (ivl, jvl, lm)
|
|
!
|
|
! extraction of angular momentum l from lp:
|
|
!
|
|
if (lp.eq.1) then
|
|
l = 1
|
|
elseif ( (lp.ge.2) .and. (lp.le.4) ) then
|
|
l = 2
|
|
elseif ( (lp.ge.5) .and. (lp.le.9) ) then
|
|
l = 3
|
|
elseif ( (lp.ge.10) .and. (lp.le.16) ) then
|
|
l = 4
|
|
elseif ( (lp.ge.17) .and. (lp.le.25) ) then
|
|
l = 5
|
|
elseif ( (lp.ge.26) .and. (lp.le.36) ) then
|
|
l = 6
|
|
elseif ( (lp.ge.37) .and. (lp.le.49) ) then
|
|
l = 7
|
|
else
|
|
call errore (' qvan ', ' lp.gt.49 ', lp)
|
|
endif
|
|
|
|
sig = (0.d0, -1.d0) ** (l - 1)
|
|
sig = sig * ap (lp, ivl, jvl)
|
|
!
|
|
qm1 = -1.0_dp ! any number smaller than qmod(1)
|
|
!
|
|
do ig = 1, ngy
|
|
!
|
|
! calculate quantites depending on the module of G only when needed
|
|
!
|
|
if (abs (qmod (ig) - qm1) > 1.0d-6) then
|
|
qm = qmod (ig) * dqi
|
|
px = qm - int (qm)
|
|
ux = 1.d0 - px
|
|
vx = 2.d0 - px
|
|
wx = 3.d0 - px
|
|
i0 = qm + 1
|
|
i1 = qm + 2
|
|
i2 = qm + 3
|
|
i3 = qm + 4
|
|
uvx = ux * vx * sixth
|
|
|
|
pwx = px * wx * 0.5d0
|
|
|
|
work = qrad (i0, ijv, l, np) * uvx * wx + &
|
|
qrad (i1, ijv, l, np) * pwx * vx - &
|
|
qrad (i2, ijv, l, np) * pwx * ux + &
|
|
qrad (i3, ijv, l, np) * px * uvx
|
|
work1 = - qrad(i0, ijv, l, np) * (ux*vx + vx*wx + ux*wx) * sixth &
|
|
+ qrad(i1, ijv, l, np) * (wx*vx - px*wx - px*vx) * 0.5d0 &
|
|
- qrad(i2, ijv, l, np) * (wx*ux - px*wx - px*ux) * 0.5d0 &
|
|
+ qrad(i3, ijv, l, np) * (ux*vx - px*ux - px*vx) * sixth
|
|
|
|
work1 = work1 * dqi
|
|
qm1= qmod (ig)
|
|
end if
|
|
|
|
dqg (ig) = dqg (ig) + sig * dylmk0 (ig, lp) * work
|
|
if (qmod (ig) > 1.d-9) dqg (ig) = dqg (ig) + &
|
|
sig * ylmk0 (ig, lp) * work1 * g (ipol, ig) / qmod (ig)
|
|
enddo
|
|
enddo
|
|
return
|
|
|
|
end subroutine dqvan2
|
|
|