Parallelization of Cumulative Reaction Probabilities

Mike Minkoff (minkoff@mcs.anl.gov), Stephen Gray (gray@tcg.anl.gov), and Al Wagner (wagner@tcg.anl.gov)

All gas phase rate constants can be constructed from the cumulative reaction probability P. For a given energy and angular momentum, P is the sum of the reaction probabilities from all accessible reactants to all accessible products. P is a highly averaged quantity, and its direct quantum mechanical calculation forms the most efficient way to obtain exact rate constants (within the errors of the underlying potential energy surface, which must be supplied as input).

There are both time-dependent and time-independent quantum dynamics methods for the direct calculation of P. These methods

were first developed in the early to mid-1990s, and new methods continue to be developed. However, as of yet, no highly scalable and efficient parallel algorithm for the computation of P has been published.

We are pursuing to different approaches based on a time-dependent approach for P and a time-independent approach for P.