mirror of https://gitlab.com/QEF/q-e.git
150 lines
4.2 KiB
Fortran
150 lines
4.2 KiB
Fortran
!
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! Copyright (C) 2001-2008 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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!-----------------------------------------------------------------------
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subroutine zstar_eu
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!-----------------------------------------------------------------------
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! calculate the effective charges Z(E,Us) (E=scf,Us=bare)
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!
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! epsil =.true. is needed for this calculation to be meaningful
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!
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!
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USE kinds, ONLY : DP
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USE cell_base, ONLY : at, bg
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USE ions_base, ONLY : nat, zv, ityp, atm
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USE io_global, ONLY : stdout
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USE io_files, ONLY : iunigk
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USE klist, ONLY : wk, xk
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USE symme, ONLY : nsym, s, irt
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USE wvfct, ONLY : npw, npwx, igk
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USE uspp, ONLY : okvan, vkb
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use noncollin_module, ONLY : npol
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USE wavefunctions_module, ONLY: evc
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USE modes, ONLY : u, nirr, npert
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USE qpoint, ONLY : npwq, nksq
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USE eqv, ONLY : dvpsi, dpsi
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USE efield_mod, ONLY : zstareu0, zstareu
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USE units_ph, ONLY : iudwf, lrdwf, iuwfc, lrwfc
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USE control_ph,ONLY : nbnd_occ, done_zeu
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USE mp_global, ONLY : inter_pool_comm, intra_pool_comm
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USE mp, ONLY : mp_sum
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implicit none
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integer :: ibnd, ipol, jpol, icart, na, nu, mu, imode0, irr, &
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imode, nrec, mode, ik
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! counters
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real(DP) :: work (3, 3, nat), weight
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! auxiliary space
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complex(DP), external :: zdotc
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! scalar product
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!
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call start_clock ('zstar_eu')
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zstareu0(:,:) = (0.d0,0.d0)
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zstareu (:,:,:) = 0.d0
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if (nksq > 1) rewind (iunigk)
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do ik = 1, nksq
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if (nksq > 1) read (iunigk) npw, igk
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npwq = npw
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weight = wk (ik)
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if (nksq > 1) call davcio (evc, lrwfc, iuwfc, ik, - 1)
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call init_us_2 (npw, igk, xk (1, ik), vkb)
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imode0 = 0
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do irr = 1, nirr
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do imode = 1, npert (irr)
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mode = imode+imode0
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dvpsi(:,:) = (0.d0, 0.d0)
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!
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! recalculate DeltaV*psi(ion) for mode nu
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!
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call dvqpsi_us (ik, u (1, mode), .not.okvan)
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do jpol = 1, 3
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nrec = (jpol - 1) * nksq + ik
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!
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! read DeltaV*psi(scf) for electric field in jpol direction
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!
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call davcio (dpsi, lrdwf, iudwf, nrec, - 1)
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do ibnd = 1, nbnd_occ(ik)
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zstareu0(jpol,mode)=zstareu0(jpol, mode)-2.d0*weight*&
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zdotc(npwx*npol,dpsi(1,ibnd),1,dvpsi(1,ibnd),1)
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enddo
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enddo
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enddo
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imode0 = imode0 + npert (irr)
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enddo
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enddo
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!
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! Now we add the terms which are due to the USPP
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!
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if (okvan) call zstar_eu_us
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#ifdef __PARA
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call mp_sum ( zstareu0, intra_pool_comm )
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call mp_sum ( zstareu0, inter_pool_comm )
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#endif
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!
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! bring the mode index to cartesian coordinates
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!
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do jpol = 1, 3
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do mu = 1, 3 * nat
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na = (mu - 1) / 3 + 1
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icart = mu - 3 * (na - 1)
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do nu = 1, 3 * nat
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zstareu (jpol, icart, na) = zstareu (jpol, icart, na) + &
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CONJG(u (mu, nu) ) * zstareu0 (jpol, nu)
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enddo
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enddo
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enddo
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!
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work(:,:,:) = 0.d0
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!
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! bring to crystal axis for symmetrization
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! NOTA BENE: the electric fields are already in crystal axis
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!
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do na = 1, nat
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do ipol = 1, 3
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do jpol = 1, 3
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do icart = 1, 3
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work (jpol, ipol, na) = work (jpol, ipol, na) + zstareu (jpol, &
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icart, na) * at (icart, ipol)
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enddo
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enddo
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enddo
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enddo
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! WRITE( stdout,'(/,10x,"Effective charges E-U in crystal axis ",/)')
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! do na=1,nat
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! WRITE( stdout,'(10x," atom ",i6)') na
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! WRITE( stdout,'(10x,"(",3f15.5," )")') ((work(jpol,ipol,na),
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! + ipol=1,3),jpol=1,3)
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! enddo
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call symz (work, nsym, s, nat, irt)
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do na = 1, nat
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call trntns (work (1, 1, na), at, bg, 1)
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enddo
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zstareu(:,:,:) = work(:,:,:)
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!
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! add the diagonal part
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!
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do ipol = 1, 3
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do na = 1, nat
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zstareu (ipol, ipol, na) = zstareu (ipol, ipol, na) + zv (ityp ( na) )
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enddo
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enddo
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done_zeu=.TRUE.
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call summarize_zeu()
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call stop_clock ('zstar_eu')
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return
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end subroutine zstar_eu
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