Phase space bottlenecks and statistical theories of isomerization reactions.

We examine the dynamics of isomerization reactions and point out the existence of important phase space bottlenecks. A three-state statistical theory based on the behavior of trajectories and the properties of the phase space bottlenecks is proposed; this theory is better than standard two-state RRKM theory under some circumstances and offers a new way of conceptualizing isomerization. We test our ideas on the simple system, consisting of an equivalent double well coupled to a Morse oscillator, which was studied by DeLeon and Berne. Approximate methods of obtaining the required elementary rate constants in our theory are also discussed. [ABSTRACT FROM AUTHOR]