Calculation of reaction probabilities and rate coefficients for collinear three-body exchange reactions using time-dependent wave packet methods

Wave packet methods are described that permit rate coefficients for the collinear A+BC exchange reaction to be obtained directly without the necessity of computing the reaction probabilities out of all statistically significant initial BC vibrational states. Similar wave packet methods are given that allow reaction probabilities at essentially fixed energy for collinear A+BC systems to be computed by time-dependent methods. The explicit integration procedure of Harmuth is utilized to evolve the wave packets. The methods are appplied to reactions occurring on three different LEPS-type potential-energy surfaces using the hydrogen atom mass for each atom and also to the T+HD→TH+D reaction on a realistic potential-energy surface. In most cases, the results are shown to be in excellent accord with exact close-coupling calculations.