mirror of https://gitlab.com/QEF/q-e.git
110 lines
3.2 KiB
Fortran
110 lines
3.2 KiB
Fortran
!
|
|
! Copyright (C) 2001 PWSCF group
|
|
! This file is distributed under the terms of the
|
|
! GNU General Public License. See the file `License'
|
|
! in the root directory of the present distribution,
|
|
! or http://www.gnu.org/copyleft/gpl.txt .
|
|
!
|
|
!
|
|
!-----------------------------------------------------------------------
|
|
subroutine polariz_vdw ( iu )
|
|
!-----------------------------------------------------------------------
|
|
!
|
|
! calculates the frequency dependent polarizability
|
|
!
|
|
|
|
USE io_global, ONLY : stdout
|
|
USE io_files, ONLY : iunigk
|
|
USE pwcom
|
|
USE kinds, ONLY : DP
|
|
USE phcom
|
|
USE cell_base, ONLY : omega
|
|
USE symme, ONLY : symmatrix, crys_to_cart
|
|
USE eff_v, ONLY : nelecr, veff, et_c, dvext, dpsi_eff
|
|
USE mp_global, ONLY : intra_pool_comm, inter_pool_comm
|
|
USE mp, ONLY : mp_sum
|
|
|
|
IMPLICIT NONE
|
|
!
|
|
! I/O variables
|
|
!
|
|
real(kind=DP) :: iu
|
|
!
|
|
! local variables
|
|
!
|
|
integer :: ibnd, ipol, jpol, nrec, ik
|
|
! counter on polarizations
|
|
! counter on records
|
|
! counter on k points
|
|
real(kind=DP) :: w, weight
|
|
|
|
complex(kind=DP) :: zdotc
|
|
|
|
call start_clock ('polariz')
|
|
epsilon(:,:) = 0.d0
|
|
if (nksq > 1) rewind (unit = iunigk)
|
|
do ik = 1, nksq
|
|
! if (nksq > 1) read (iunigk) npw, igk
|
|
weight = nelecr !wk (ik)
|
|
w = fpi * weight / omega
|
|
do ipol = 1, 3
|
|
! nrec = (ipol - 1) * nksq + ik
|
|
! call davcio (dvpsi, lrebar, iuebar, nrec, - 1)
|
|
do jpol = 1, 3
|
|
! nrec = (jpol - 1) * nksq + ik
|
|
! call davcio (dpsi, lrdwf, iudwf, nrec, - 1)
|
|
do ibnd = 1, nbnd_occ (ik)
|
|
!
|
|
! this is the real part of <DeltaV*psi(E)|DeltaPsi(E)>
|
|
!
|
|
epsilon(ipol,jpol)=epsilon(ipol,jpol)-4.d0*w*REAL( &
|
|
zdotc (npw, dvext (1, ipol, ibnd), 1, dpsi_eff (1, jpol, ibnd), 1) )
|
|
enddo
|
|
enddo
|
|
enddo
|
|
enddo
|
|
#ifdef __PARA
|
|
call mp_sum ( epsilon, intra_pool_comm )
|
|
call mp_sum ( epsilon, inter_pool_comm )
|
|
#endif
|
|
!
|
|
! symmetrize
|
|
!
|
|
! WRITE( stdout,'(/,10x,"Unsymmetrized in crystal axis ",/)')
|
|
! WRITE( stdout,'(10x,"(",3f15.5," )")') ((epsilon(ipol,jpol),
|
|
! + ipol=1,3),jpol=1,3)
|
|
call crys_to_cart (epsilon)
|
|
call symmatrix (epsilon)
|
|
!
|
|
! pass to cartesian axis
|
|
!
|
|
! WRITE( stdout,'(/,10x,"Symmetrized in cartisian axis ",/)')
|
|
! WRITE( stdout,'(10x,"(",3f15.5," )")') ((epsilon(ipol,jpol),
|
|
! + ipol=1,3),jpol=1,3)
|
|
!
|
|
! add the diagonal part
|
|
!
|
|
do ipol = 1, 3
|
|
epsilon (ipol, ipol) = epsilon (ipol, ipol) + 1.d0
|
|
enddo
|
|
!
|
|
! compute the polarization
|
|
!
|
|
do ipol = 1, 3
|
|
do jpol = 1, 3
|
|
if ( epsilon (ipol, jpol) .gt. 1d-5) &
|
|
epsilon (ipol, jpol) = (3.d0*omega/fpi) * ( epsilon (ipol, jpol) - 1.d0 ) / &
|
|
( epsilon (ipol, jpol) + 2.d0 )
|
|
enddo
|
|
enddo
|
|
!
|
|
! and print the result
|
|
!
|
|
WRITE( stdout, '(/,10x,"Polarizability in cartesian axis at frequency ",f5.2,/)') iu
|
|
|
|
WRITE( stdout, '(10x,"(",3f18.9," )")') ((epsilon(ipol,jpol), ipol=1,3), jpol=1,3)
|
|
call stop_clock ('polariz')
|
|
|
|
return
|
|
end subroutine polariz_vdw
|