From reaction dynamics to chemical kinetics

The calculation of thermal rate constants from the outcome of dynamics calculations is discussed. Then, approximate methods for modeling the kinetics of chemical reactions directly from the features of the potential-energy surface bypassing dynamics calculations, are illustrated with reference to reactions of astrochemical interest. In particular, the capture model for barrierless association reactions and the Rice–Ramsperger–Kassel–Marcus (RRKM) theory of unimolecular reactions are discussed. Finally, a master-equation approach for merging the different elementary steps involved in a complex reaction mechanism is illustrated.