mirror of https://gitlab.com/QEF/q-e.git
145 lines
4.4 KiB
Fortran
145 lines
4.4 KiB
Fortran
!
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! Copyright (C) 2002-2003 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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#include "f_defs.h"
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!
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!----------------------------------------------------------------------
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subroutine gen_at_dy ( ik, natw, lmax_wfc, u, dwfcat )
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!----------------------------------------------------------------------
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!
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! This routines calculates the atomic wfc generated by the derivative
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! (with respect to the q vector) of the spherical harmonic. This quantity
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! is needed in computing the the internal stress tensor.
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!
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USE kinds, ONLY : DP
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USE parameters, ONLY : nchix
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USE io_global, ONLY : stdout
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USE constants, ONLY : tpi, fpi
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USE atom, ONLY : msh, r, rab, lchi, nchi, oc, chi
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USE ions_base, ONLY : nat, ntyp => nsp, ityp, tau
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USE cell_base, ONLY : omega, at, bg, tpiba
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USE klist, ONLY : xk
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USE gvect, ONLY : ig1, ig2, ig3, eigts1, eigts2, eigts3, g
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USE wvfct, ONLY : npw, npwx, igk
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USE us, ONLY : tab_at, dq
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!
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implicit none
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!
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! I/O variables
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!
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integer :: ik, natw, lmax_wfc
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real (kind=DP) :: u(3)
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complex (kind=DP) :: dwfcat(npwx,natw)
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!
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! local variables
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!
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integer :: ig, na, nt, nb, l, lm, m, i, iig, ipol, iatw, i0, i1, i2, i3
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real (kind=DP) :: arg, vqint, px, ux, vx, wx
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complex (kind=8) :: phase, pref
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real (kind=DP), allocatable :: q(:), gk(:,:), dylm(:,:), dylm_u(:,:), &
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vchi(:), auxjl(:), chiq(:,:,:)
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! q(npw), gk(3,npw),
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! dylm (npw,(lmax_wfc+1)**2),
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! dylm_u(npw,(lmax_wfc+1)**2),
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! vchi(ndm),
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! auxjl(ndm),
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! chiq(npwx,nchix,ntyp),
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complex (kind=DP), allocatable :: sk(:)
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! sk(npw)
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allocate ( q(npw), gk(3,npw), chiq(npwx,nchix,ntyp) )
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dwfcat(:,:) = (0.d0,0.d0)
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do ig = 1,npw
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gk (1, ig) = xk (1, ik) + g (1, igk (ig) )
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gk (2, ig) = xk (2, ik) + g (2, igk (ig) )
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gk (3, ig) = xk (3, ik) + g (3, igk (ig) )
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q (ig) = gk(1, ig)**2 + gk(2, ig)**2 + gk(3, ig)**2
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end do
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allocate ( dylm_u(npw,(lmax_wfc+1)**2) )
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allocate ( dylm(npw,(lmax_wfc+1)**2) )
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dylm_u(:,:) = 0.d0
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do ipol=1,3
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call dylmr2 ((lmax_wfc+1)**2, npw, gk, q, dylm, ipol)
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call DAXPY(npw*(lmax_wfc+1)**2,u(ipol),dylm,1,dylm_u,1)
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end do
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deallocate (dylm)
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q(:) = sqrt ( q(:) ) * tpiba
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!
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! here we compute the radial fourier transform of the chi functions
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!
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do nt = 1,ntyp
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do nb = 1,nchi(nt)
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if (oc(nb,nt) >= 0.d0) then
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l = lchi(nb,nt)
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do ig = 1, npw
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px = q (ig) / dq - int (q (ig) / dq)
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ux = 1.d0 - px
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vx = 2.d0 - px
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wx = 3.d0 - px
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i0 = q (ig) / dq + 1
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i1 = i0 + 1
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i2 = i0 + 2
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i3 = i0 + 3
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chiq(ig,nb,nt) = tab_at (i0, nb, nt) * ux * vx * wx / 6.d0 + &
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tab_at (i1, nb, nt) * px * vx * wx / 2.d0 - &
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tab_at (i2, nb, nt) * px * ux * wx / 2.d0 + &
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tab_at (i3, nb, nt) * px * ux * vx / 6.d0
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enddo
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endif
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enddo
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enddo
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allocate ( sk(npw) )
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iatw=0
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do na = 1,nat
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nt = ityp(na)
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arg=(xk(1,ik)*tau(1,na)+xk(2,ik)*tau(2,na)+xk(3,ik)*tau(3,na))*tpi
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phase=DCMPLX(cos(arg),-sin(arg))
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do ig =1,npw
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iig = igk(ig)
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sk(ig) = eigts1(ig1(iig),na) * &
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eigts2(ig2(iig),na) * &
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eigts3(ig3(iig),na) * phase
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end do
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do nb = 1,nchi(nt)
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if (oc(nb,nt) >= 0.d0) then
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l = lchi(nb,nt)
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pref = (1.d0,0.d0)**l
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pref = (0.d0,1.d0)**l
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do m = 1,2*l+1
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lm = l*l+m
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iatw = iatw+1
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do ig=1,npw
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dwfcat(ig,iatw) = chiq(ig,nb,nt) * sk(ig) * &
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dylm_u(ig,lm) * pref / tpiba
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end do
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enddo
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end if
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enddo
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enddo
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if (iatw.ne.natw) then
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WRITE( stdout,*) 'iatw =',iatw,'natw =',natw
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call errore('gen_at_dy','unexpected error',1)
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end if
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deallocate (sk)
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deallocate (dylm_u)
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deallocate ( q, gk, chiq )
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return
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end subroutine gen_at_dy
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