Global nine-dimensional potential energy surface for the H-5 system. II. Fit to an analytical expression

A global nine-dimensional potential energy surface (GPES) for the adiabatic ground state of the H-5 system which fits the ab initio data, reported in the previous paper of this series, has been obtained (root-mean-square erro r 2.2 kcal/mol). The global fitting procedure is an extension of the corres ponding procedure for triatomic and tetra-atomic systems including the func tional form previously proposed by the authors. The H-5 GPES obtained here is totally symmetric with respect to permutations of the hydrogen atoms and satisfies the criteria needed to be used in scattering calculations. (C) 1 999 American Institute of Physics. [S0021-9606(99)30816-3].