A MP2/6-31G* direct dynamics simulation is used to study the dynamics of the central barrier [Cl-C2H5-ClI- for the Cl- + C2H5 SN2 reaction. The majority of the trajectories move off the central barrier to form the Cl -C2H5Cl--C2H 5Cl complex and appear to undergo efficient IVR as assumed by RRKM theory. However, some of the trajectories move directly to products without forming the complex, a non-RRKM result. A hydrogen atom link-atom QM/MM model is described for studying the dynamics of [X-CH2R-Y]- central barriers with the -R substituent. The model is used to calculate vibrational frequencies for the [Cl-C2H5-Cl]- central barrier.
- Central barrier dynamics
- Direct dynamics classical trajectories
- QM/MM model
- RRKM theory
- S2 reaction dynamics