subroutine ne2hsur(r,vt)
c  generates pairwise additive potential for Ne2H system.
c  coordinates are not mass scaled.
c  r(1) is the distance between atoms in the diatom Ne2.
c  r(2) and r(3) are the Ne-H distances.
c  Hartree atomic units on everything.
      implicit none
      character*8 procname
      parameter (procname='ne2sur  ')
      real*8 r, vt, vneh, vnene
c  ------1---------2---------3---------4---------5---------6---------7--
      external vneh, vnene
      dimension r(3)
      save
c
c  *******calculate potential.
       vt = vnene(r(1)) + vneh(r(2)) + vneh(r(3))
c  the following is a special case that turns off the neh interactions.
c       vt = vnene(r(1))
c  the following special case turns off the nene interaction and one of the vneh.
c       vt =  vneh(r(3))
c  the following special case turns off the nene interaction.
c      vt = vneh(r(2)) + vneh(r(3))
c  the following is a special case that turns off all interactions.
c      vt = 0.d0
c
      return
      end