Quasiclassical trajectory study of O(1D) + N2O --> NO + NO: classification of reaction paths and vibrational distribution.

Quasiclassical trajectory calculations for the planar reaction of O(1D) + N2O --> NO + NO are performed on a newly constructed ab initio potential energy surface. In spite of the reduced dimension approximation, the agreement between the computational and experimental results is largely satisfactory, especially on the similar amount of excitation of the two kinds of NO products found by Akagi et al. [J. Chem. Phys. 111, 115 (1999)]. Analyzing the initial condition dependence of the trajectories, we find that the trajectories of this reaction can be classified into four reaction paths, which correspond to respective areas in the space of initial condition. In one of the four paths, a long-lived stable complex is formed in the course of reaction, whereas the other three paths have direct mechanism. Contradictory to conventional understanding of the chemical reaction dynamics, the direct paths show more efficient energy exchange between the NO stretching modes than that with a long-lived intermediate. This indicates that the vibrational mode coupling along the short-lived paths is considerably stronger than expected.