mirror of https://gitlab.com/QEF/q-e.git
143 lines
4.4 KiB
Fortran
143 lines
4.4 KiB
Fortran
!
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! Copyright (C) 2001-2007 Quantum-Espresso 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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subroutine addusstres (sigmanlc)
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!----------------------------------------------------------------------
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!
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! This routine computes the part of the atomic force which is due
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! to the dependence of the Q function on the atomic position.
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!
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USE kinds, ONLY : DP
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USE ions_base, ONLY : nat, ntyp => nsp, ityp
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USE cell_base, ONLY : omega, tpiba
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USE gvect, ONLY : nr1, nr2, nr3, nrx1, nrx2, nrx3, nrxx, ngm, &
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nl, nlm, gg, g, eigts1, eigts2, eigts3, ig1, ig2, ig3
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USE lsda_mod, ONLY : nspin
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USE scf, ONLY : v, vltot
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USE uspp, ONLY : becsum, okvan
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USE uspp_param, ONLY : upf, lmaxq, nh, nhm
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USE control_flags, ONLY : gamma_only
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!
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implicit none
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!
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real(DP) :: sigmanlc (3, 3)
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! the nonlocal stress
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integer :: ig, nt, ih, jh, ijh, ipol, jpol, is, na
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! counter on g vectors
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! counter on mesh points
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! number of composite nm components
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! the atom type
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! counter on atomic beta functions
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! counter on atomic beta functions
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! composite index for beta function
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! counter on polarizations
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! counter on polarizations
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! counter on spin polarizations
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! counter on atoms
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complex(DP), allocatable :: aux(:,:), aux1(:), vg(:), qgm(:)
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complex(DP) :: cfac
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! used to contain the potential
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! used to compute a product
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! used to contain the structure fac
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real(DP) :: ps, DDOT, sus(3,3)
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real(DP) , allocatable :: qmod(:), ylmk0(:,:), dylmk0(:,:)
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! the integral
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! the ultrasoft part of the stress
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! the modulus of G
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! the spherical harmonics
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! the spherical harmonics derivativ
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! of V_eff and dQ
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! function which compute the scal.
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allocate ( aux(ngm,nspin), aux1(ngm), vg(nrxx), qgm(ngm), qmod(ngm) )
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allocate ( ylmk0(ngm,lmaxq*lmaxq), dylmk0(ngm,lmaxq*lmaxq) )
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!
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sus(:,:) = 0.d0
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!
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call ylmr2 (lmaxq * lmaxq, ngm, g, gg, ylmk0)
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do ig = 1, ngm
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qmod (ig) = sqrt (gg (ig) )
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enddo
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!
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! fourier transform of the total effective potential
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!
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do is = 1, nspin
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if ( nspin == 4 .and. is /= 1 ) then
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!
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vg(:) = v%of_r(:,is)
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!
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ELSE
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!
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vg(:) = vltot(:) + v%of_r(:,is)
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!
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END IF
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call cft3 (vg, nr1, nr2, nr3, nrx1, nrx2, nrx3, - 1)
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do ig = 1, ngm
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aux (ig, is) = vg (nl (ig) )
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enddo
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enddo
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!
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! here we compute the integral Q*V for each atom,
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! I = sum_G i G_a exp(-iR.G) Q_nm v^*
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! (no contribution from G=0)
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!
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do ipol = 1, 3
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call dylmr2 (lmaxq * lmaxq, ngm, g, gg, dylmk0, ipol)
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do nt = 1, ntyp
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if ( upf(nt)%tvanp ) then
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ijh = 1
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do ih = 1, nh (nt)
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do jh = ih, nh (nt)
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call dqvan2 (ngm, ih, jh, nt, qmod, qgm, ylmk0, dylmk0, ipol)
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do na = 1, nat
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if (ityp (na) == nt) then
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!
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do is = 1, nspin
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do jpol = 1, ipol
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do ig = 1, ngm
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cfac = aux (ig, is) * &
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CONJG( eigts1 (ig1 (ig), na) * &
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eigts2 (ig2 (ig), na) * &
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eigts3 (ig3 (ig), na) )
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aux1 (ig) = cfac * g (jpol, ig)
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enddo
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!
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! and the product with the Q functions
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!
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ps = omega * DDOT (2 * ngm, aux1, 1, qgm, 1)
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sus (ipol, jpol) = sus (ipol, jpol) - &
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ps * becsum (ijh, na, is)
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enddo
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enddo
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endif
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enddo
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ijh = ijh + 1
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enddo
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enddo
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endif
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enddo
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enddo
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if (gamma_only) then
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sigmanlc(:,:) = sigmanlc(:,:) + 2.d0*sus(:,:)
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else
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sigmanlc(:,:) = sigmanlc(:,:) + sus(:,:)
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end if
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deallocate (ylmk0, dylmk0)
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deallocate (aux, aux1, vg, qgm, qmod)
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return
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end subroutine addusstres
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