Ab initio, variational transition state theory and quasiclassical trajectory study on the lowest (2)A ' potential energy surface involved in the N(D-2)+O-2(X (3)Sigma(-)(g))-> O(P-3) plus NO(X (2)Pi) atmospheric reaction

A CASSCF and CASPT2 ab initio study has been carried out for the lowest (2) A' potential energy surface (2 (2)A' PES) that correlates reactants and pro ducts of the N(D-2)+O-2-->O(P-3)+NO reaction. All the stationary points hav e been characterized and along with a grid of more than 600 ab initio point s have been fitted to an analytical function. Afterwards, this analytical P ES has been employed to study the kinetics [variational transition state th eory (VTST) and quasiclassical trajectory (QCT) methods] and dynamics (QCT method) of the reaction. Concerning the rate constants, a good agreement wi th the experimental values corresponding to the global deactivation of N(D- 2) has been obtained. This suggests that this reaction is responsible of mo st of the reactivity of the N(D-2)+O-2 system. NO vibrational distributions have also been calculated. Although there is not a good agreement between the theoretical and experimental values, preliminary results show that they can become quite close by taking into account the contribution of the 1 (2 )A' PES. (C) 2001 American Institute of Physics.