A centrifugal sudden distorted wave study of the Cl + HCl → ClH + Cl reaction: Results for a scaled and fitted ab initio potential energy surface having a noncollinear reaction path

We present the results of a centrifugal sudden distorted wave (CSDW) quantum scattering study of the reaction Cl + HCl → ClH + Cl. The potential energy surface used in this calculation (denoted sf-POLCI) has been chosen to fit a scaled ab initio surface for Cl-H-Cl angles greater than 150° (angles for which the latter surface has been determined), and to fit an extended London-Eyring-Polanyi-Sato (LEPS) surface at smaller angles. This sf-POLCI surface has a noncollinear Cl-H-Cl saddle point with a Cl-H-Cl angle of 161.4°. We also compare our CSDW results with those from a LEPS surface, which has a collinear geometry saddle point, but is otherwise similar to the sf-POLCI surface. Results presented include partial wave reaction probabilities, integral and differential cross sections, product rotational distributions, and thermal rate coefficients. The sf-POLCI results are generally similar to the LEPS results, although there are a few important differences. In particular, the integral cross sections in the threshold region increase more slowly with energy for the sf-POLCI surface. As a result, the activation energy is smaller for the LEPS surface, even though it has the higher barrier. Both the sf-POLCI and LEPS cross sections exhibit high product rotational excitation, with the sf-POLCI products more excited than the LEPS. Also, the rotational state which contributes most to the thermal rate coefficient is higher for the sf-POLCI surface than for the LEPS. For both surfaces the CSDW rate coefficients agree with experiment within the experimental uncertainties.