mirror of https://gitlab.com/QEF/q-e.git
102 lines
2.9 KiB
Fortran
102 lines
2.9 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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!-----------------------------------------------------------------------
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subroutine dielec()
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!-----------------------------------------------------------------------
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!
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! calculates the dielectric tensor
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!
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USE kinds, only : DP
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USE io_global, ONLY : stdout
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USE constants, ONLY: fpi
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USE cell_base, ONLY: omega
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USE klist, ONLY: wk
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USE symme, ONLY: symmatrix, crys_to_cart
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USE wvfct, ONLY: npwx
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USE buffers, ONLY : get_buffer
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USE noncollin_module, ONLY : npol
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USE efield_mod, ONLY : epsilon
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USE units_ph, ONLY : lrdwf, iudwf, lrebar, iuebar
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USE eqv, ONLY : dpsi, dvpsi
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USE qpoint, ONLY : nksq, ikks
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USE ph_restart, ONLY : ph_writefile
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USE control_lr, ONLY : nbnd_occ
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USE control_ph, ONLY : done_epsil, epsil
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USE mp_pools, ONLY : inter_pool_comm
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USE mp_bands, ONLY : intra_bgrp_comm
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USE mp, ONLY : mp_sum
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implicit none
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integer :: ibnd, ipol, jpol, nrec, ik, ikk, ierr
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! counter on polarizations
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! counter on records
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! counter on k points
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real(DP) :: w, weight
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IF (.NOT.epsil.OR.done_epsil) RETURN
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call start_clock ('dielec')
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epsilon(:,:) = 0.d0
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do ik = 1, nksq
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ikk=ikks(ik)
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weight = wk (ikk)
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w = fpi * weight / omega
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do ipol = 1, 3
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nrec = (ipol - 1) * nksq + ik
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call get_buffer(dvpsi, lrebar, iuebar, nrec)
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do jpol = 1, 3
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nrec = (jpol - 1) * nksq + ik
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call get_buffer (dpsi, lrdwf, iudwf, nrec)
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do ibnd = 1, nbnd_occ (ikk)
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!
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! this is the real part of <DeltaV*psi(E)|DeltaPsi(E)>
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!
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! FIXME: use zgemm instead of dot_product
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epsilon(ipol,jpol)=epsilon(ipol,jpol)-4.d0*w* DBLE( &
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dot_product(dvpsi(:,ibnd),dpsi(:,ibnd)) )
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enddo
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enddo
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enddo
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enddo
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call mp_sum ( epsilon, intra_bgrp_comm )
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call mp_sum ( epsilon, inter_pool_comm )
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!
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! symmetrize
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!
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! WRITE( stdout,'(/,10x,"Unsymmetrized in crystal axis ",/)')
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! WRITE( stdout,'(10x,"(",3f15.5," )")') ((epsilon(ipol,jpol),
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! + ipol=1,3),jpol=1,3)
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call crys_to_cart (epsilon)
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call symmatrix ( epsilon )
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!
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! pass to cartesian axis
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!
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! WRITE( stdout,'(/,10x,"Symmetrized in cartesian axis ",/)')
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! WRITE( stdout,'(10x,"(",3f15.5," )")') ((epsilon(ipol,jpol),
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! + ipol=1,3),jpol=1,3)
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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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epsilon (ipol, ipol) = epsilon (ipol, ipol) + 1.d0
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enddo
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!
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! and print the result
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!
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done_epsil=.TRUE.
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CALL summarize_epsilon()
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CALL ph_writefile('tensors',0,0,ierr)
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call stop_clock ('dielec')
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return
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end subroutine dielec
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