Effects of Reagent Rotational Excitation on OH+HCl→Cl+H₂O Reaction^†

Potential-averaged five-dimensional (PA5D) time-dependent wave packet calculations have been carried out to obtain the initial state-specific reaction probabilities and rate constants for a series of reactant rotationally excited states of the title reaction on one of our recently developed potential energy surface (F12a PES). It is found that individual excitation of the reactant HCl to j₁=2 or OH to j₂=1 yields the largest total reaction probability except for low collision energies. In the low energy region, the resonance enhancement of reaction probability decreases rapidly with the increase of OH rotational excitation, resulting in a rapid decline in the rate constant below 250 K. The rate constant of the simultaneous HCl and OH rotational excitation is not a simple superposition of the results of the separate excitation. Finally, we obtain the thermal rate constants of the reaction by Boltzmann averaging the rate constants for initial rotational states up to (5, 5), which are in reasonable agreement with the experimental results.