Quantum-classical correspondence in the O(3P)+HCl and Cl(2P)+OH reactions for total angular momentum J=0

Abstract

A method for carrying out quasiclassical trajectory (QCT) calculations of A+BC(v,j) reactive collisions for the special case of the total angular momentum J=0 is described. Since quantum reactive scattering calculations involving heavier atoms are not straightforward for the J>0 case, this method is useful to establish the extent to which classical mechanics is applicable to a particular reaction. The method is tested by comparing the results of trajectory calculations for the J=0 case with analogous quantum-mechanical (QM) calculations for the O(3P)+HCl reaction and the reverse reaction Cl(2P)+OH. The S4 potential surface, which is based on MRCI+Q/cc-pVTZ energies scaled by the scaled external correlation method [B. Ramachandran et al., J. Chem. Phys. 111, 3862 (1999)], is used for these calculations. The QCT and QM cumulative reaction probabilities are found to be in good agreement, especially for the Cl+OH reaction. The agreement between the two types of state-resolved reaction probabilities is less striking but improves considerably as the initial diatomic rotational quantum number j increases. A comparison is also made between the exact and J-shifted QCT thermal rate coefficients. These are found to be in excellent agreement, which is in keeping with similar agreement observed in the case of the quantum-mechanical exact and J-shifted thermal rate coefficients.