Classical and quantum reaction probabilities and thermal rate constants for the collinear H+H 2 exchange reaction with vibrational excitation

Abstract

Classical trajectory calculations for the collinear H+H 2 exchange reaction were performed using the same potential energy surface previously adopted for exact quantum mechanical calculations. Reactions of both ground state and vibrationally excited state reagent were considered, over a relative kinetic energy range sufficient to produce vibrational excitation of products. At energies close to threshold the classical and quantum mechanical reaction probabilities differ sufficiently to cause a major difference in the corresponding thermal rate constants at low temperatures. Effective reaction thresholds differ by 0.07 eV for ground state and 0.09 eV for excited state reagent. At energies substantially above threshold the quantum reaction probabilities oscillate around the corresponding classical ones. However, some classical curves also show oscillatory behavior, suggesting caution in the assignment of oscillations in the quantum curves to quantum effects.