Reduced-dimensionality quantum calculations of the thermal rate coefficient for the Cl+HCl r arrow ClH+Cl reaction: Comparison with centrifugal-sudden distorted wave, coupled channel hyperspherical, and experimental results

Reduced dimensionality (RD) cumulative reaction probabilities (CRPs) are reported for the Cl+HCl{r arrow}ClH+Cl reaction using two semiempirical extended London--Eyring--Polanyi--Sato potential energy surfaces. Comparison is made with CRPs from centrifugal-sudden distorted wave (CSDW) calculations, and with accurate coupled channel hyperspherical (CCH) CRPs for total angular momentum quantum number {ital J}=0. Rotational and bending energy-shift approximations are applied to the CCH CRPs for {ital J}=0 to obtain approximate CRPs for {ital J}{gt}0. A test of this approximation is made using CSDW partial wave CRPs. New expressions for the thermal rate coefficient are derived using these approximations. The rate coefficients calculated from RD and energy-shifted CCH CRPs are in excellent agreement with each other. They also agree well with the CSDW and experimental rate coefficients.