ROLE OF ZERO-POINT ENERGY CHANGES IN H-2-SURFACE COLLISIONS - APPLICATION TO CU(111) AND PT(111)

The temporal variation of the zero-point energy of H-2 produces dynamical features that add to the electronic molecule-surface interaction. The softening of the H-H bond when the molecule is near the surface gives rise to a virtual attractive potential well, while the hindering of molecular rotations at the surface produces a virtual potential barrier for dissociation. However, these two effects partially cancel each other. The present results are based on ab initio potentials deduced from total energy cluster calculations.