subroutine surface(v,rij)
!-----------------------------------------------------------------------
! This routine supplies the potential energy surface for the
! reactive scattering codes.
!
! On entering: The arrary rij contains the internuclear distances
!              in units of bohr (NOT mass scaled).
!
!              The common /pes/ must contain a character string
!              of length 25 that properly describes the potential.
!
! On Exit:     The variable v is the value of the potential energy
!              surface in Hartree atomic units.
!
!
!-----------------------------------------------------------------------
USE PES_Module
implicit none
real*8 v,rij, tmud2
dimension rij(3)
external tmud2
character(LEN=25) potname
!-----------------------------------------------------------------------
!  The character string potname must contain a string that uniquely
!  specifies the potential energy surface to be used.
!-----------------------------------------------------------------------
data potname/'tmud2 pairwise add. '/
!-----------------------------------------------------------------------
! Check for correct potential energy surface specification.
!-----------------------------------------------------------------------
if(PES_Name.ne.potname)then
   write(6,304)PES_Name,potname
304   format(1h ,2a25)
   write(6,*)'***error***: Execution stopped in routine surface'
   write(6,*)'The potential energy surface name does not match',' the name in the potential energy surface routine.'
stop 'surface'
end if
!-----------------------------------------------------------------------
! This call to surfac supplies the potential energy surface
! for the particular system of interest.
!-----------------------------------------------------------------------
v=tmud2(rij)
return
end