********************************************************************************
*                                                                              *
*  2DHF version 1-2003                                                         *
*  Copyright (C) 1996  Jacek Kobus, Leif Laaksonen, Dage Sundholm              *
*                                                                              *
*  This software may be used and distributed according to the terms            *
*  of the GNU General Public License, see README and COPYING.                  *
*                                                                              *
********************************************************************************
c ### relax ###
c
c     Controls relaxation of Coulomb potentials, exchange potentials
c     and orbitals
c
      subroutine  relax (iorb,cw_sor,psi,pot,excp,
     &     borb,bpot,d,e,f0,f1,f2,f3,f4,g,wjac1,wjac2,
     &     wgt2,lhs,rhs,wk00,wk0,wk1,wk2)
      implicit integer*4 (i-n)
      implicit real*8 (a-h,o-z)
      real*8 lhs
      integer*4 cw_sor		
c_mpi
      include 'mpif.h'
      include 'commons_mpi.inc'
c_mpi
      include 'commons8.inc'

      dimension psi(*),pot(*),excp(*)
      dimension wjac1(*),wjac2(*),borb(*),bpot(*),d(*),e(*),
     &     f0(*),f1(*),f2(*),f3(*),f4(*),g(*),wgt2(*),
     &     lhs(*),rhs(*),wk00(*),wk0(*),wk1(*),wk2(*)

      call MPI_COMM_RANK( MPI_COMM_WORLD, myid, ierr )
      call MPI_COMM_SIZE( MPI_COMM_WORLD, numprocs, ierr )

c     when ipoiss=2,3 then mcsor method is used to solve poisson's eqs for
c     potentials

c      if (myid.ne.0) then
c         call dcopy(length3,cw_exch_mpi,1,excp,1)
c      endif
      if (myid.eq.0) then
         if (exlcoul.eq.0.d0) then
            if (ipoiss.eq.1) then
               call relcoul1 (iorb,cw_sor,psi,pot,excp,bpot,d,f3,g,
     &              lhs,rhs,wk2)
            elseif (ipoiss.eq.2.or.ipoiss.eq.3) then
               call relcoul2 (iorb,cw_sor,psi,pot,excp,bpot,d,f3,g,
     &              lhs,rhs,wk2)
            endif	  
         endif
      endif

c     process the exchange potentials
c     prepare a load for every node
      call preprelexch(iorb)
      call prepload(iorb)

      if (islat.eq.0) then
         if (exlexp.eq.0.d0.or.exlexp.eq.2.d0) then
            if (ipoiss.eq.1) then
               call relexch1 (iorb,cw_sor,psi,pot,excp,bpot,d,e,
     &              f3,g,lhs,rhs,wk2)
            elseif (ipoiss.eq.2.or.ipoiss.eq.3) then
               call relexch2 (iorb,cw_sor,psi,pot,excp,bpot,d,e,
     &              f3,g,lhs,rhs,wk2)
            endif
	 endif
      endif
      call MPI_BARRIER( MPI_COMM_WORLD,ierr )

      if (myid.eq.0) then
         if (exlorb.eq.0.d0) then
            if (ipoiss.eq.1.or.ipoiss.eq.3) then
               call relorb1(iorb,cw_sor,psi,pot,excp,borb,d,e,
     &              f0,f1,f2,f4,wgt2,lhs,rhs,wk00,wk0,wk2)
            elseif (ipoiss.eq.2) then
               call relorb2(iorb,cw_sor,psi,pot,excp,borb,d,e,
     &              f0,f1,f2,f4,wgt2,lhs,rhs,wk00,wk0,wk2)
            endif
         endif
      endif

      return
      end