O 2H isomerization: potential energy surface topography and classical dynamical study

Abstract

The potential energy surface of the molecular system O 2H is analysed within the framework of both the reaction path and the adiabatic path descriptions, for two differently parametrized potential energy surfaces as given by Varandas et al. The aim is the investigation of the dynamics of the isomerization process. In the reaction path analysis difficulties arise in the region close to the O 2H absolute minimum; this problem is studied with the help of a simple two-dimensional model revealing some general properties of the way in which a reaction path approaches a minimum of the potential energy surface. Concerning the dynamics of the isomerization process, the trajectory calculations are very sensitive to relatively subtle features of the potential energy surface: Depending on the potential energy surface used, the isomerizatin process turns out to be either quasiperiodic or intrinsically chaotic. We illustrate this situation by means of a spectral analysis of classical trajectories and we also calculate how frequent the isomerization process occurs in dependence on the initial distribution of the available energy among the various modes of the system.