Classical trajectory simulations of post-transition state dynamics

Abstract

Classical chemical dynamics simulations of post-transition state dynamics are reviewed. Most of the simulations involve direct dynamics for which the potential energy and gradient are obtained directly from an electronic structure theory. The chemical reaction attributes and chemical systems presented are product energy partitioning for Cl⁻ ··· CH₃Br → ClCH₃ + Br⁻ and C₂H₅F → C₂H₄ + HF dissociation, non-RRKM dynamics for cyclopropane stereomutation and the Cl⁻ ··· CH₃Cl complexes mediating the Cl⁻ + CH₃Cl S_N2 nucleophilic substitution reaction, and non-IRC dynamics for the OH⁻ + CH₃F and F⁻ + CH₃OOH chemical reactions. These studies illustrate the important role of chemical dynamics simulations in understanding atomic-level reaction dynamics and interpreting experiments. They also show that widely used paradigms and model theories for interpreting reaction kinetics and dynamics are often inaccurate and are not applicable.

Keywords:

• chemical dynamics
• unimolecular reaction dynamics
• potential energy surfaces
• non-RRKM dynamics
• non-IRC dynamics

Acknowledgements

The research described here was supported by the National Science Foundation under multiple grants and by the Robert A. Welch Foundation under Grant No. D-0005.