quantum-espresso/D3/dqrhod2v.f90

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!
! 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 dqrhod2v (ipert, drhoscf)
!-----------------------------------------------------------------------
! calculates the term containing the second variation of the potential
! and the first variation of the charge density with respect to a
! perturbation at a generic q
!
#include "machine.h"
use pwcom
use phcom
use d3com
#ifdef __PARA
use para
#endif
implicit none
integer :: ipert
complex (8) :: drhoscf (nrxx)
! the variation of the charge density
!
! local variables
!
integer :: icart, jcart, na_icart, na_jcart, na, ng, nt, &
ik, ikk, ikq, ig, ibnd, nu_i, nu_j, nu_k, ikb, jkb, nrec, ios
! index of the perturbation associated with drho
! counter on polarizations
! counter on polarizations
! counter on modes
! counter on modes
! counter on atoms
! counter on G vectors
! counter on atomic types
! counter on k points
! counter on k points
! counter on k+q points
! counter on G vectors
! counter on bands
! counter on modes
! counter on modes
! counter on modes
! counters on beta functions
! record position of dwfc
! integer variable for I/O control
real (8) :: gtau, wgg
! the product G*\tau_s
! the weight of a K point
complex (8) :: ZDOTC, fac, alpha (8), work
complex (8), allocatable :: d3dywrk (:,:), work0 (:), &
work1 (:), work2 (:), work3 (:), work4 (:), work5 (:), work6 (:)
! work space
allocate (d3dywrk( 3 * nat, 3 * nat))
allocate (work0( nrxx))
allocate (work1( npwx))
allocate (work2( npwx))
allocate (work3( npwx))
allocate (work4( npwx))
allocate (work5( npwx))
allocate (work6( npwx))
call setv (2 * 9 * nat * nat, 0.0d0, d3dywrk, 1)
!
! Here the contribution deriving from the local part of the potential
#ifdef __PARA
! ... computed only by the first pool (no sum over k needed)
!
if (mypool.ne.1) goto 100
#endif
!
call ZCOPY (nrxx, drhoscf, 1, work0, 1)
call cft3 (work0, nr1, nr2, nr3, nrx1, nrx2, nrx3, - 1)
do na = 1, nat
do icart = 1, 3
na_icart = 3 * (na - 1) + icart
do jcart = 1, 3
na_jcart = 3 * (na - 1) + jcart
do ng = 1, ngm
gtau = tpi * ( (xq (1) + g (1, ng) ) * tau (1, na) + &
(xq (2) + g (2, ng) ) * tau (2, na) + &
(xq (3) + g (3, ng) ) * tau (3, na) )
fac = DCMPLX (cos (gtau), - sin (gtau) )
d3dywrk (na_icart, na_jcart) = d3dywrk (na_icart, na_jcart) &
- tpiba2 * omega * (xq (icart) + g (icart, ng) ) * &
(xq (jcart) + g (jcart, ng) ) * &
vlocq (ng, ityp (na) ) * fac * conjg (work0 (nl (ng) ) )
enddo
enddo
enddo
enddo
#ifdef __PARA
call reduce (2 * 9 * nat * nat, d3dywrk)
!
! each pool contributes to next term
!
100 continue
#endif
!
! Here we compute the nonlocal (Kleinman-Bylander) contribution.
!
rewind (unit = iunigk)
do ik = 1, nksq
read (iunigk, err = 200, iostat = ios) npw, igk
200 call errore ('dqrhod2v', 'reading igk', abs (ios) )
if (lgamma) then
ikk = ik
ikq = ik
npwq = npw
else
ikk = 2 * ik - 1
ikq = 2 * ik
read (iunigk, err = 300, iostat = ios) npwq, igkq
300 call errore ('dqrhod2v', 'reading igkq', abs (ios) )
endif
wgg = wk (ikk)
call davcio (evc, lrwfc, iuwfc, ikk, - 1)
!
! In metallic case it necessary to know the wave function at k+q point
! so as to correct dpsi. dvpsi is used as working array
!
if (degauss.ne.0.d0) call davcio (dvpsi, lrwfc, iuwfc, ikq, -1)
call init_us_2 (npwq, igkq, xk (1, ikq), vkb)
call init_us_2 (npw, igk, xk (1, ikk), vkb0)
!
! Reads the first variation of the wavefunction projected on conduction
!
nrec = (ipert - 1) * nksq + ik
call davcio (dpsi, lrdwf, iudqwf, nrec, - 1)
!
! In the metallic case corrects dpsi so as that the density matrix
! will be: Sum_{k,nu} 2 * | dpsi > < psi |
!
if (degauss.ne.0.d0) then
nrec = ipert + (ik - 1) * 3 * nat
call davcio (psidqvpsi, lrpdqvp, iupdqvp, nrec, - 1)
call dpsi_corr (dvpsi, psidqvpsi, ikk, ikq, ipert)
endif
!
do icart = 1, 3
do jcart = 1, 3
do ibnd = 1, nbnd
do ig = 1, npw
work1(ig)=evc(ig,ibnd)*tpiba*(xk(icart,ikk)+g(icart,igk(ig)))
work2(ig)=evc(ig,ibnd)*tpiba*(xk(jcart,ikk)+g(jcart,igk(ig)))
work5(ig)= work1(ig)*tpiba*(xk(jcart,ikk)+g(jcart,igk(ig)))
enddo
do ig = 1, npwq
work3(ig)=dpsi(ig,ibnd)*tpiba*(xk(icart,ikq)+g(icart,igkq(ig)))
work4(ig)=dpsi(ig,ibnd)*tpiba*(xk(jcart,ikq)+g(jcart,igkq(ig)))
work6(ig)= work3(ig)*tpiba*(xk(jcart,ikq)+g(jcart,igkq(ig)))
enddo
jkb=0
do nt = 1, ntyp
do na = 1, nat
if (ityp (na).eq.nt) then
na_icart = 3 * (na - 1) + icart
na_jcart = 3 * (na - 1) + jcart
do ikb = 1, nh (nt)
jkb = jkb+1
alpha(1) = ZDOTC(npw, work1, 1,vkb0(1,jkb), 1)
alpha(2) = ZDOTC(npwq,vkb(1,jkb), 1, work4, 1)
alpha(3) = ZDOTC(npw, work2, 1,vkb0(1,jkb), 1)
alpha(4) = ZDOTC(npwq,vkb(1,jkb), 1, work3, 1)
alpha(5) = ZDOTC(npw, work5, 1,vkb0(1,jkb), 1)
alpha(6) = ZDOTC(npwq,vkb(1,jkb),1,dpsi(1,ibnd),1)
alpha(7) = ZDOTC(npw, evc(1,ibnd),1,vkb0(1,jkb),1)
alpha(8) = ZDOTC(npwq,vkb(1,jkb),1,work6, 1)
#ifdef __PARA
call reduce(16, alpha)
#endif
d3dywrk(na_icart,na_jcart) = d3dywrk(na_icart,na_jcart) &
+ conjg(alpha(1) * alpha(2) + alpha(3) * alpha(4) - &
alpha(5) * alpha(6) - alpha(7) * alpha(8) ) &
* dvan (ikb, ikb, nt) * wgg * 2.0d0
enddo
endif
enddo
end do
end do
enddo
enddo
enddo
#ifdef __PARA
call poolreduce (2 * 9 * nat * nat, d3dywrk)
#endif
!
! Rotate the dynamical matrix on the basis of patterns
! some indices do not need to be rotated
!
nu_k = ipert
do nu_i = 1, 3 * nat
if (q0mode (nu_i) ) then
do nu_j = 1, 3 * nat
work = (0.0d0, 0.0d0)
do na = 1, nat
do icart = 1, 3
na_icart = 3 * (na - 1) + icart
do jcart = 1, 3
na_jcart = 3 * (na - 1) + jcart
work = work + ug0 (na_icart, nu_i) * &
d3dywrk (na_icart,na_jcart) * u (na_jcart, nu_j)
enddo
enddo
enddo
d3dyn (nu_i, nu_k, nu_j) = d3dyn (nu_i, nu_k, nu_j) + work
d3dyn (nu_i, nu_j, nu_k) = d3dyn (nu_i, nu_j, nu_k) + conjg(work)
enddo
endif
enddo
deallocate (work6)
deallocate (work5)
deallocate (work4)
deallocate (work3)
deallocate (work2)
deallocate (work1)
deallocate (work0)
deallocate (d3dywrk)
return
end subroutine dqrhod2v