SOLVENT DYNAMICS - MODIFIED RICE-RAMSPERGER-KASSEL-MARCUS THEORY .2. VIBRATIONALLY ASSISTED CASE

Expressions are given for a solvent dynamics-modified Rice-Ramsperger- Rassel-Marcus (RRKM) theory for clusters. The role of vibrational assi stance across the transition state region is included. The usual diffe rential equation for motion along the slow coordinate X in constant te mperature systems is modified so as to apply to microcanonical systems . A negative entropy term, -S-v(X), replaces the (1/T)partial derivati ve U/partial derivative X or (1/T)partial derivative G/partial derivat ive X which appears in canonical systems. Expressions are obtained for the RRKM-type rate constant k(X) and for the S-v(X) which appear in t he differential equation. An approximate solution for steady-state con ditions is given for the case that the ''reaction window'' is narrow. The solution then takes on a simple functional form. The validity of t he assumption can be checked a posteriori. Recrossings of the transiti on state are included and the condition under which the treatment appr oaches that in Part I is described. (C) 1996 American Institute of Phy sics.