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.