We report quasiclassical trajectory calculations for the reaction N(4 S) + O 2 f 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 2 A′ states of NO 2 , improved via a multiple energy-switching scheme to attain nearspectroscopic accuracy in the vicinity of the deep X 2 A 1 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.

The effect of reactants vibrational and rotational excitation on products (HO 2 + O and O 3 + H) formation is investigated for the title reaction by using the quasiclassical trajectory method and the realistic double manybody expansion (DMBE) potential energy surface for ground-state HO 3. It is shown that it can be a potential source of ozone in the upper atmosphere.

Quasi-classical trajectories have been integrated to study the vibrational relaxation of the O + NO(V) process as a function of the initial vibrational quantum number for T ) 298 K, 1500 K, and 3000 K. Two reliable potential energy surfaces have been employed for the A′ and A′′ doublet states of NO 2 . The calculated vibrational relaxation rate constants show a nearly V-independent behavior at room temperature and a moderate increase with V for higher temperatures. Although deviating significantly from the recommended values, good agreement with recent experimental results has been obtained. The importance of multi-quantum transitions is also analyzed.

We report a theoretical study of the title four-atom atmospheric reaction for a range of translational energies 0.1 e E tr /kcal mol-1 e 40 and the range 13 e V′′ e 27 of vibrational quantum numbers of the oxygen molecule. All calculations have employed the quasiclassical trajectory method, and a realistic potential energy surface obtained by using the double many-body expansion (DMBE) method for ground-state HO 3 .

We investigate the effect of vibrational excitation on the dynamics and kinetics of the atmospheric reaction O( 3 P) + HO 2 f OH + O 2 using two double many-body expansion potential energy surfaces previously reported. The results show that such an effect is relatively minor even considering HO 2 with contents of vibrational excitation close to the H + O 2 dissociation asymptote. It should therefore not bear drastic implications in atmospheric modeling where such an effect has been ignored thus far.