mirror of https://gitlab.com/QEF/q-e.git
153 lines
4.6 KiB
Fortran
153 lines
4.6 KiB
Fortran
!
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! Copyright (C) 2002 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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!-----------------------------------------------------------------------
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subroutine dndtau(dns,ldim,alpha,ipol)
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!-----------------------------------------------------------------------
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!
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! This routine computes the derivative of the ns with respect to the ionic
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! displacement u(alpha,ipol) used to obtain the Hubbard contribution to the
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! atomic forces.
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!
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#include "machine.h"
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USE atom, ONLY: nchi, lchi, oc
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USE basis, ONLY: nat, natomwfc, ityp
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USE klist, ONLY: nks, xk
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USE lsda_mod, ONLY: lsda, nspin, current_spin, isk
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USE ldaU, ONLY: swfcatom, Hubbard_l, Hubbard_U, Hubbard_alpha
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USE wavefunctions_module, ONLY : evc
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USE us, ONLY: nkb, vkb
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USE wvfct, ONLY: nbnd, npwx, npw, igk, wg
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use becmod
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use io_files
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#ifdef __PARA
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use para
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#endif
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implicit none
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integer :: &
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ik, & ! counter on k points
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ibnd, & ! " " bands
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is, & ! " " spins
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i, na, nt, n, alpha, ipol, counter, m1,m2, l
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integer :: ldim
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real (kind=DP) :: &
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dns(ldim,ldim,nspin,nat)
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complex (kind=DP) :: ZDOTC, c_one, c_zero
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integer, allocatable :: offset(:)
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! offset(nat): offset of d electrons of atom d in the natomwfc ordering
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complex (kind=DP), allocatable :: &
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proj(:,:), wfcatom(:,:), spsi(:,:),dproj(:,:)
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! proj(natomwfc,nbnd), wfcatom(npwx,natomwfc),
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! spsi(npwx,nbnd), dproj(natomwfc,nbnd)
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CALL start_clock('dndtau')
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allocate ( offset(nat) )
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allocate ( proj(natomwfc,nbnd), dproj(natomwfc,nbnd), &
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spsi(npwx,nbnd), wfcatom(npwx,natomwfc), becp(nkb,nbnd) )
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!
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! D_Sl for l=1 and l=2 are already initialized, for l=0 D_S0 is 1
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!
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counter = 0
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do na=1,nat
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offset(na) = 0
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nt=ityp(na)
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do n=1,nchi(nt)
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if (oc(n,nt) >= 0.d0) then
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l=lchi(n,nt)
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if (l == Hubbard_l(nt)) offset(na) = counter
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counter = counter + 2 * l + 1
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end if
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end do
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end do
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if(counter.ne.natomwfc)call errore('new_ns','nstart<>counter',1)
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dns(:,:,:,:) = 0.d0
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!
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! we start a loop on k points
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!
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if (nks.gt.1) rewind (iunigk)
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do ik = 1, nks
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if (lsda) current_spin = isk(ik)
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!
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! now we need the first derivative of proj with respect to tau(alpha,ipol)
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!
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if (nks.gt.1) read (iunigk) npw, igk
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call davcio(evc,nwordwfc,iunwfc,ik,-1)
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call davcio(swfcatom,nwordatwfc,iunat,ik,-1)
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c_one= (1.d0, 0.d0)
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c_zero = (0.d0, 0.d0)
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call ZGEMM ('C', 'N', natomwfc, nbnd, npw, c_one, &
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swfcatom, npwx, evc, npwx, c_zero, proj, natomwfc)
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#ifdef __PARA
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call reduce(2*natomwfc*nbnd,proj)
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#endif
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call init_us_2 (npw,igk,xk(1,ik),vkb)
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call ccalbec(nkb, npwx, npw, nbnd, becp, vkb, evc)
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call s_psi (npwx, npw, nbnd, evc, spsi )
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call atomic_wfc( ik, wfcatom )
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dproj(:,:) = (0.d0,0.d0)
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call dprojdtau(dproj,wfcatom,spsi,alpha,ipol,offset(alpha))
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!
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! compute the derivative of occupation numbers (the quantities dn(m1,m2))
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! of the atomic orbitals. They are real quantities as well as n(m1,m2)
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!
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do na = 1,nat
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nt = ityp(na)
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if (Hubbard_U(nt).ne.0.d0.or.Hubbard_alpha(nt).ne.0.d0) then
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do m1 = 1,ldim
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do m2 = m1,ldim
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do ibnd = 1,nbnd
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dns(m1,m2,current_spin,na) = dns(m1,m2,current_spin,na) + &
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wg(ibnd,ik) * &
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DREAL( proj(offset(na)+m1,ibnd) * &
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conjg(dproj(offset(na)+m2,ibnd)) + &
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dproj(offset(na)+m1,ibnd) * &
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conjg(proj(offset(na)+m2,ibnd)) )
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end do
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end do
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end do
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end if
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end do
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end do ! on k-points
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#ifdef __PARA
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call poolreduce(ldim*ldim*nspin*nat,dns)
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#endif
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!
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! impose hermiticity of dn_{m1,m2}
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!
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do na = 1,nat
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do is = 1,nspin
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do m1 = 1,ldim
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do m2 = m1+1,ldim
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dns(m2,m1,is,na) = dns(m1,m2,is,na)
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end do
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end do
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end do
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end do
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deallocate ( proj, dproj, spsi, wfcatom, becp )
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deallocate ( offset )
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CALL stop_clock('dndtau')
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return
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end subroutine dndtau
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