!
! Copyright (C) 2009 Quantum ESPRESSO 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 initialize_gw()
  !-----------------------------------------------------------------------
  !
  ! This is a driver to the GW initialization routine. Again ever so slightly adapted from phonon initialization
  !
  USE klist,  ONLY : nks
  USE qpoint, ONLY : nksq, ikks, ikqs
  USE control_gw, ONLY : lgamma

  IMPLICIT NONE
  INTEGER :: ik

  !
  ! ... nksq is the number of k-points, NOT including k+q points
  !
   IF ( lgamma ) THEN
      !
      nksq = nks
      ALLOCATE(ikks(nksq), ikqs(nksq))
      DO ik=1,nksq
         ikks(ik) = ik
         ikqs(ik) = ik
      ENDDO
     !
   ELSE
     !
      nksq = nks / 2
      ALLOCATE(ikks(nksq), ikqs(nksq))
      DO ik=1,nksq
         ikks(ik) = 2 * ik - 1
         ikqs(ik) = 2 * ik
      ENDDO
      !
   END IF
  !
  !Allocate the gw variables
  !
  CALL allocate_gwq()
  !
  !Set the main control variable of the gw code
  !
  CALL gwq_setup()
  !
  !Open Relevant GW files
  CALL openfilq()
  !Initialize all quantities which do not depend on the 
  !linear response to the perturbation
  !All necessary quantities to describe the local and nonlocal 
  !pseudopotential in the GW program.
  !
  CALL gwq_init()
  !
  CALL print_clock( 'GW' )
  !
  RETURN
END SUBROUTINE initialize_gw