Solvent dynamics-modified RRKM theory in clusters

Kramers and RRKM theories are used to formulate a solvent dynamics-modified treatment of unimolecular reaction rates in clusters. The canonical Kramersʹ description is modified so as to apply to microcanonical systems. An entropic gradient, arising from all coordinates but the reaction coordinate q, and a q-dependent microcanonical vibrational temperature are introduced. A simple expression is obtained relating the rate constant to its RRKM value and permitting comparison with recent experiments. An application is also made to the Kramersʹ turnover region.