SUBROUTINE Surface(Vtot,rij)
  USE Numeric_Kinds_Module
  USE PES_Module
  IMPLICIT NONE
  CHARACTER(LEN=25) PotName
  REAL*8 Vtot, rij, r4pot
  DIMENSION rij(3), r4pot(3)
  EXTERNAL VLiH2
  !-----------------------------------------------------------------------
  !  The character string potname must contain a string that uniquely
  !  specifies the potential energy surface to be used.
  !-----------------------------------------------------------------------
  DATA PotName/'LiH2_Gianturco_Pot'/

  !-----------------------------------------------------------------------
  ! Check for correct potential energy surface specification.
  !-----------------------------------------------------------------------
  IF(Pes_Name.ne.PotName)THEN
    WRITE(6,*)'Pes_Name is not equal to PotName.'
    WRITE(6,*)'***error***: Execution stopped in routine surface: VLiH2'
    WRITE(6,'(1x,A)')' Name read in from input data:  ', Pes_Name
    WRITE(6,'(1x,A)')' Name of the potential energy surface routine:  ',PotName
    STOP 'surface: VLiH2'
  ENDIF

  !-----------------------------------------------------------------------
  ! This call to surfac supplies the potential energy surface
  ! for the particular system of interest.
  !-----------------------------------------------------------------------
  r4Pot(1)=rij(3)
  r4Pot(2)=rij(1)
  r4Pot(3)=rij(2)
  CALL VLiH2_Gianturco(r4pot,Vtot) !The total energy is the collision energy for Li+H2 (v=0,j=0)
  RETURN
ENDSUBROUTINE Surface