Dynamics Study of the N(4S) + O2 Reaction and Its Reverse

Abstract

We report quasiclassical trajectory calculations for the reaction N(4S) + O2 → NO + O by focusing on the rovibrational distributions of the NO product molecule at a collisional energy of 3 eV and the temperature dependence of the rate constant. The calculations employ the lowest adiabatic sheet of a recently reported (Varandas, A. J. C. J. Chem. Phys. 2003, 119, 2596) multisheeted double many-body expansion potential energy surface for the 2A‘ states of NO2, improved via a multiple energy-switching scheme to attain near-spectroscopic accuracy in the vicinity of the deep 2A1 minimum. For the quartet state, the calculations employ single-sheeted potentials from various sources, except for the rate constant where the results are taken from the literature. The rate constant for the reverse endothermic reaction is calculated by dividing the rate constant for the forward reaction by the equilibrium constant calculated using statistical mechanics. For both reactions, the agreement with the recommended rate constants is good. The vibrational distributions of NO are found to agree with previously reported theoretical estimates, which show fair agreement with the general trends observed from experiment.