subroutine surfaca(v,rij)
      use pes_module
c
c
c-----------------------------------------------------------------------
c This routine supplies the potential energy surface for the
c reactive scattering codes.
c
c On entering: The array rij contains the internuclear distances
c              in units of bohr (NOT mass scaled).
c
c              pesname must contain a character string
c              of length 20 that properly describes the potential.
c
c On Exit:     The variable v is the value of the potential energy
c              surface in Hartree atomic units.
c
c
c-----------------------------------------------------------------------
      implicit none
      real*8 v, rij(3),vnene
      character(len=25) potname 
c-----------------------------------------------------------------------
c Check for correct potential energy surface specification.
c-----------------------------------------------------------------------
      if(pesname.ne.potname)then
      write(*,*)'The potential energy surface name does not',
     >       ' match the name in the potential energy surface routine.'
      write(*,*)'***error***: Execution stopped in routine',
     >                  ' surface'
      write(*,*) 'pesname=', pesname
      write(*,*) 'potname=', potname
      stop 'surfaca'
      end if
c-----------------------------------------------------------------------
c This call to surfac supplies the potential energy surface
c for the particular system of interest.
c-----------------------------------------------------------------------
c  the following just produces the Ne-Ne potential.
      v = vnene(rij(1))
c  the following is a special case
c     v=0
      return
      end