Quasiclassical trajectory simulation of the O(1D)+HCl→OH+Cl, ClO+H reactions on an improved potential energy surface

The CASSCF (complete active space self-consistent field) and MRCI (multi-reference configuration interaction) ab initio points of Hernandez et al. (J. Chem. Phys., 1996, 105, 2710) have been supplemented with new calculations of the same level of theory at selected geometries, and the whole set was used to fit an improved ground (1(1)A') potential energy surface (PES) for the O(D-1) + HCl system. The points were fitted by a polynomial expansion in bond order coordinates, and the electronic excitation of the isolated oxygen atom was taken care of by a proper, smooth lowering of the HCl potential at long internuclear distances. This ensures a common dissociation to all ground state atoms. On the fitted surface quasiclassical trajectories have been run under conditions similar to those of the experiment. A very good agreement with beam data of Balucani et al. (Chem. Phys. Lett., 1991, 180, 34) was found for the LAB (laboratory frame) angular distribution and the time-of-flight spectra of ClO. A good agreement with the infrared chemiluminescence and laser induced fluorescence data of Kruus et al. (J. Chem. Phys., 1988, 88, 985) was found for the inverted vibrational distribution of the OH product.