The photofragmentation of simple van der Waals complexes. Classical statistical theory and comparison with exact classical and approximate quantum dynamics results

Abstract

A recently proposed statistical theory for unimolecular reactions, based on employing approximate phase-space bottlenecks as transition states, is discussed and a new and simpler expression for the rate constant is derived. The theory is applied to a collinear model of van der Waals molecule fragmentation and the results are compared with exact classical and approximate quantum-mechanical rate constants. Sources of non-statistical behaviour and classical/quantum-mechanical discrepancy are discussed.