A THEORETICAL-STUDY OF THE DISSOCIATION OF NO2

A combination of ab initio quantum chemical and variational Rice-Ramsperger-Kassel-Marcus (RRKM) theory calculations are employed in a detailed theoretical modeling of the NO2 dissociation process. Estimates of the interaction energies between NO and O in the transition state region are obtained at the multireference singles and doubles configuration interaction level employing a 6-31G* basis set. A two-dimensional variational optimization of the transition state number of states is performed-employing an analytic potential energy function obtained from a fit to the present quantum chemical data. The resulting theoretical estimates of the energy resolved rate constants and product vibrational distributions are compared with the corresponding experimentally determined values. The effect of quantum mechanics on the number of states is considered via a comparison of quantum and semiclassical evaluations for an assumed center-of-mass separation distance reaction coordinate.