A split interaction representation for quantum correlation functions of dissociative systems

We propose and test a new general approach to the ℒ 2 evaluation of quantum correlation functions for dissociative systems. This method introduces a split interaction representation (SIR) for the correlation function based on formally exact manipulations, and greatly enhances convergence of the correlation function with respect to the range of the ℒ 2 basis, by suppressing the spurious ‘‘reflections’’ from the ‘‘edges’’ of the basis. The method is tested by applying it for the evaluation of flux autocorrelation function from which the quantal thermal rate constant is obtained by integrating it over time. Computations for the one-dimensional Eckart barrier show remarkable convergence of the flux autocorrelation function with respect to both the size and the range of the basis.