Dynamics of the Collinear H+H2 Reaction. II. Energy Analysis

Abstract

Quantitative comparisons and evaluations of the classical and quantal dynamics of the collinear H+H₂ reaction are presented. The variation of classical and quantal reaction probabilities with average initial kinetic energy is shown in a series of graphs. In addition, both a quantal wavepacket and a classical ensemble are analyzed in the reactant, product, and interaction regions to determine their average kinetic and vibrational energies. Classical mechanics gives an amazingly good prediction of many detailed properties for over half of the time that reaction occurs. Included are such properties as the time dependence of the reaction probability, vibrational energy of the H₃ intermediate, and the kinetic energy for motion across the symmetric stretch line on the potential surface. At late times these classical predictions show derivations from their quantal counterparts. The late time behavior of the reaction is mysterious in the sense that we do not have simple models which predict the differences between the classical and quantal calculations.