Determination of the bottleneck regions of potential energy surfaces for atom transfer reactionsby variational transition state theory

Variational transition-state theory (VTST) is used to help identify the regions of potential energy surfaces (PES) that are most important in determining reliable rate constants. A wide variety of model PES are studied to predict general trends for various reaction types. The relationship between classical and quantum mechanical rate calculations is discussed, using the generalized transition-state theory (GTST). The classical and quantal-ground- state endoergicities and the vibrationally adiabatic ground-state (VAG) barrier heights are summarized. The application of VTST to three-dimensional reactions uses the canonical variational theory (CVT) and improved canonical variational theory (ICVT). The RMBEBO model was used to generate a wide variety of PES. Reactions were surveyed on RMBEBO and other surfaces. The rate constant calculated by applying the transition state assumption at the dynamical bottleneck of a reaction is often quite different from that calculated by conventional TST. In many cases, one can estimate what kind and size of effects will be important for a reaction with given saddle point properties and masses