Uniform J-shifting approach for calculating reaction rate constant

This paper presents a new uniform J-shifting approach for accurate calculation of rate constant in quantum dynamics study of chemical reaction. Instead of using a fixed shifting constant B in the standard J-shifting approach, the current method employs a temperature-dependent shifting constant which is obtained through an optimization procedure at a given temperature. By utilizing the calculated reaction probabilities at only a few total angular momentum values of J, the current approach automatically gives uniformly accurate rate constant across the entire range of temperature. Numerical studies of several benchmark reaction systems, including the H + H-2, H-2 + OH and H-2 + CN reactions, show explicitly that the uniform J-shifting approach is far superior to the standard J-shifting approach and it provides a robust method for accurate and efficient calculation of reaction rate constant in rigorous quantum dynamics study of chemical reaction. (C) 1999 American Institute of Physics. [S0021-9606(99)01816-4].