Direct dynamics simulations of O(3P) + HCl at hyperthermal collision energies

The dynamics of the O(3P) + HCl reaction at hyperthermal collision energies were investigated using the quasiclassical trajectory method. Stationary points on the OClH 3A" and 3A' potential energy surfaces (PESs) were also examined. The lowest transition state leading to OCl + H on the 3A" surface is 2.26 eV above the reagents at the CCSD(T)/cc-pVTZ level of theory. This saddle point is bent and product-like. Direct dynamics calculations at the MP2/cc-pVTZ level of theory were used to investigate the excitation functions for OH + Cl, OCl + H, and O + H + Cl formation. OCl is formed mainly from small-impact-parameter collisions, and the OCl + H excitation function peaks around 5 eV, where it is similar in magnitude to the OH + Cl excitation function. The shape of the OCl + H excitation function is discussed, and features are identified that should be general to hyperthermal collision dynamics.