GLOBAL POTENTIAL-ENERGY SURFACES FROM LIMITED ABINITIO DATA

Two new potential energy surfaces for modeling the dynamics of the reaction OH + H2 --> H2O + H are presented. While the form of these surfaces is relatively simple, varying the surface parameters along the reaction path allows these surfaces to reproduce the ab initio information of Walch and Dunning as well as either the barrier shape computed by Dunning, Harding, and Kraka or the experimental rate constants of Ravishankara et al. By comparing the results obtained from these surfaces and an earlier one by Schatz and Elgersma, we are able to study the sensitivity of the predicted dynamics on both the form of the surface and the data to which the surface is fit. In particular, the results indicate that both the barrier shape and the degree of reaction path curvature can strongly influence the predicted rate constants at lower temperatures.