Monte Carlo Calculation of Triatomic Dissociation Rates. I. N2O and O3

Abstract

A very fast digital computer was used to simulate the motion of nonrotating triatomic molecules. Starting configurations were selected by a weighted random procedure which leads to correctly averaged dissociation rate constants vs energy. Trajectories were followed for 90 026 starting configurations representing various harmonic and anharmonic models of N2O and O3. The conventional normal-mode description is very poor for all models studied; nevertheless, harmonic models give rise to large numbers of ``uninteresting'' molecules. The computations support a random gap assumption for anharmonic models only. It is concluded that calculations based on harmonic models give unrealistic rate constants below a pressure of about 100 atm for these molecules, and that the computed results are best described by a modified Rice—Kassel type of theory with a generalized postulate of limited molecular anharmonicity.