mirror of https://gitlab.com/QEF/q-e.git
93 lines
2.6 KiB
Fortran
93 lines
2.6 KiB
Fortran
!
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! Copyright (C) 2001 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 set_efsh (drhoscf, imode0, irr, npe)
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!-----------------------------------------------------------------------
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! This routine calculates the FermiEnergy shift
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! and stores it in the variable ef_sh
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!
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#include "f_defs.h"
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USE kinds, only : DP
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USE io_global, ONLY : stdout
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use pwcom
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use phcom
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use d3com
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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 :: npe, imode0, irr
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! input: the number of perturbation
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! input: the position of the current mode
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! input: index of the current irr. rep.
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complex (DP) :: drhoscf (nrxx, npe)
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! input: variation of the charge density
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integer :: ipert, ik, ikk, ibnd
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! counters
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complex (DP) :: delta_n, def (npertx)
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! the change in electron number
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! the change of the Fermi energy for each perturbation
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real (DP) :: weight, wdelta
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! kpoint weight
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! delta function weight
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real (DP), save :: dos_ef
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! density of states at Ef
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real (DP), external :: w0gauss
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logical, save :: first = .true.
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! Used for initialization
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!
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! first call: calculates density of states at Ef
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!
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if (first) then
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first = .false.
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dos_ef = 0.d0
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do ik = 1, nksq
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if (lgamma) then
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ikk = ik
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else
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ikk = 2 * ik - 1
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endif
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weight = wk (ikk)
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do ibnd = 1, nbnd
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wdelta = w0gauss ( (ef - et (ibnd, ikk) ) / degauss, ngauss) &
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/ degauss
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dos_ef = dos_ef + weight * wdelta
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enddo
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enddo
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#ifdef __PARA
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call mp_sum( dos_ef, inter_pool_comm )
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#endif
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endif
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!
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! determines Fermi energy shift (such that each pertubation is neutral)
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!
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WRITE( stdout, * )
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do ipert = 1, npe
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call cft3 (drhoscf (1, ipert), nr1, nr2, nr3, nrx1, nrx2, nrx3, - 1)
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#ifdef __PARA
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delta_n = (0.d0, 0.d0)
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if (gg (1) < 1.0d-8) delta_n = omega * drhoscf (nl (1), ipert)
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call mp_sum ( delta_n, intra_pool_comm )
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#else
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delta_n = omega * drhoscf (nl (1), ipert)
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#endif
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def (ipert) = - delta_n / dos_ef
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enddo
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!
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! symmetrizes the Fermi energy shift
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!
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call sym_def1 (def, irr)
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do ipert = 1, npe
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ef_sh (imode0 + ipert) = DBLE (def (ipert) )
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enddo
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WRITE( stdout, '(5x,"Pert. #",i3,": Fermi energy shift (Ry) =", &
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& 2f10.4)') (ipert, def (ipert) , ipert = 1, npe)
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return
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end subroutine set_efsh
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