We present a simple, yet remarkably accurate, approximate formula for the calculation of cumulative reaction probabilities and chemical reaction rates based on a separable-rotation approximation. The method allows a calculation of the full rate constant based on results for a single value of the total angular momentum J, and a criterion for selecting an appropriate value of J is provided. The method is tested for the D+H2 reaction by new accurate quantal calculations of the cumulative reaction probability and by comparisons employing previous accurate quantal calculations of rate constants. The rate constants predicted from results with a single value of J agree with full calculations to within 5% for reaction rates up to 1500 K.
Bibliographical noteFunding Information:
This work wass upportedin part by the National ScienceF oundationa nd NASA.