Centrifugal-sudden hyperspherical study of Cl + HCl → ClH + Cl reaction dynamics on ‘tight-bend’ and ‘loose-bend’ potential energy surfaces

A centrifugal-sudden hyperspherical (CSH) quantum calculation has been carried out for the three-dimensional reaction CI + HCl → ClH + Cl, using the extended London -Eyring-Polanyi-Sato (LEPS) potential energy surface no. 3 of Persky and Komweitz (PK3), which is an example of a 'tight-bend' surface. Quantities calculated include: state-to-state and cumulative reaction probabilities, and differential and integral cross sections. Comparison is made with CSH results from the ‘loose-bend’ LEPS surface of Bondi-Connor-Manz-Romelt (BCMR). Three simple models are used to understand qualitatively trends in the computed results from the PK3 and BCMR surfaces: (1) a classical hard-sphere model, which describes collisions of the reactants, (2) a J shift approximation for the reaction probabilities, where J is the total angular momentum quantum number, (3) a semi-classical optical model for the reactive differential cross sections. In addition, the angular distributions are analysed by an (asymptotic) nears ide-farside (NF) theory in order to extract their physical content. The NF analysis shows that high frequency oscillations in the forward-angle scattering are an interference effect caused by a resonance.