Journal of physical chemistry vol:100 issue:26 pages:10956-10966
In this article we present a theoretical approach to the kinetic analyses of chemical reactions by combining quantum chemical calculations with a quantum statistical treatment of rate constants. We first briefly outline the quantum Rice-Ramsperger-Kassel (QRRK) model and describe the ab initio molecular orbital methods employed. We then discuss a sampling of the studies recently carried out in the Laboratory of Quantum Chemistry, University of Leuven. We focus on some prototypical reactions of atmospheric interest including CH3 + NO, SiH3 + NO, H + HNCO, and SiH2 + C2H2(C2D2). All these reactions are multichannel processes with competing pathways. The good performance of the QRRK treatment in calculating apparent rate constants and thus extracting finer details about reaction mechanisms is demonstrated by comparison with available experimental data. Overall, the observed performance and the less tedious computing work compared to rigorous RRKM methods promote a general use of the QRRK treatment coupled with reliable ab initio calculations in kinetic analysis.