quantum-espresso/PHonon/Gamma/drhodv.f90

63 lines
1.5 KiB
Fortran

!
! Copyright (C) 2003 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 drhodv(nu_i)
!-----------------------------------------------------------------------
!
! calculate the electronic term <psi|dv|dpsi> of the dynamical matrix
!
USE mp_pools, ONLY : intra_pool_comm
USE mp, ONLY : mp_sum
USE klist, ONLY : wk, ngk
USE wvfct, ONLY : nbnd, npwx
USE cgcom
IMPLICIT NONE
INTEGER :: nu_i
!
INTEGER :: nu_j, ibnd, ik, npw
real(DP) :: dynel(nmodes), work(nbnd)
!
CALL start_clock('drhodv')
!
dynel(:) = 0.d0
ik = 1
npw = ngk(ik)
!
!** calculate the dynamical matrix (<DeltaV*psi(ion)|\DeltaPsi(ion)>)
!
DO nu_j = 1,nmodes
!
! DeltaV*psi(ion) for mode nu_j is recalculated
!
CALL dvpsi_kb(ik,nu_j)
!
! this is the real part of <DeltaV*Psi(ion)|DeltaPsi(ion)>
!
CALL pw_dot('N',npw,nbnd,dvpsi,npwx,dpsi ,npwx,work)
DO ibnd = 1,nbnd
dynel(nu_j) = dynel(nu_j) + 2.0d0*wk(ik)*work(ibnd)
ENDDO
ENDDO
#if defined(__MPI)
CALL mp_sum( dynel, intra_pool_comm )
#endif
!
! NB this must be done only at the end of the calculation!
!
DO nu_j = 1,nmodes
dyn(nu_i,nu_j) = - (dyn(nu_i,nu_j)+dynel(nu_j))
ENDDO
!
CALL stop_clock('drhodv')
!
RETURN
END SUBROUTINE drhodv