Collision Dynamics and the Statistical Theories of Chemical Reactions. II. Comparison of Reaction Probabilities

The reaction probability obtained as a function of total energy from transition-state theory for classical collinear atom, diatomic-molecule exchange reactions is compared with the results of trajectory calculations for the same potential surface. For a well-defined barrier in the symmetric H, H2 reaction, there is excellent agreement up to rather high energies. Other reactions (e.g., H2+Br⇄HBr+H) yield considerably larger deviations; these can be shown to result from a transmission coefficient that is less than unity, from a nonequilibrium distribution in the transition region, or from both effects.