Calculation of partial widths and isotope effects for reactive resonances by a reaction-path Hamiltonian model: Test against accurate quantal results for a twin-saddle point system Journal Article

Overview

We calculate the partial widths of three collisional resonances in a collinear system with mass combinations HFH and DFD on a low-barrier model potential energy surface. We compare accurate quantal results to results obtained with a reaction-path Hamiltonian model in which the resonances are interpreted as quasibound states trapped in wells of adiabatic potential curves and their decay probabilities are calculated by semiclassical tunneling calculations and a Feshbach golden-rule formula with the decay mediated by an internal centrifugal interaction proportional to the curvature of the reaction path. The model successfully predicts when vibrationally nonadiabatic decay dominates over the adiabatic mechanism for decomposition of the resonances and it predicts the nonadiabatic partial widths with an average error of 25%.