SUBROUTINE surfaca(v,rij)
USE Numeric_Kinds_Module
USE PES_MODULE
USE Fileunits_Common_Module
!
!
!-----------------------------------------------------------------------
! This routine supplies the potential energy surface for the
! reactive scattering codes.
!
! On entering: The array rij contains the internuclear distances
!              in units of bohr (NOT mass scaled).
!
!              PES_Name must contain a CHARACTER string
!              of length 20 that properly describes the potential.
!
! On Exit:     The variable v is the value of the potential energy
!              surface in Hartree atomic units.
!
!
!-----------------------------------------------------------------------
IMPLICIT NONE
REAL(Kind=WP_Kind) v, rij(3),vnene
CHARACTER(LEN=25) potname
!-----------------------------------------------------------------------
!  The CHARACTER string potname must contain a string that uniquely
!  specifies the potential energy surface to be used.
!-----------------------------------------------------------------------
data potname/'Ne2H pairwise    PES'/
!-----------------------------------------------------------------------
! Check for correct potential energy surface specification.
!-----------------------------------------------------------------------
IF(PES_Name/=potname)THEN
WRITE(out_unit,*)'The potential energy surface name does not',     &
        ' match the name in the potential energy surface routine.'
WRITE(out_unit,*)'***error***: Execution stopped in routine',      &
                   ' surface'
WRITE(out_unit,*) 'PES_Name=', PES_Name
WRITE(out_unit,*) 'potname=', potname
STOP 'potname'
ENDIF
!-----------------------------------------------------------------------
! This CALL to surfac supplies the potential energy surface
! for the particular system of interest.
!-----------------------------------------------------------------------
!  the following just produces the Ne-Ne potential.
v = vnene(rij(1))
!  the following is a special case
!     v=0
RETURN
END