Femtosecond dynamics of transition states: the classical saddle-point barrier reactions

In this Letter, we report molecular dynamics studies of the transition state (A+BC) of saddle-point barrier reactions. We compare the theoretical findings with direct experimental observation of reaction times and kinetic energy distributions for the IHgI system. The results account for the dynamics of two- and three-body recoil from the transition state to final products and elucidate the nature of concerted (symmetric) and non-concerted (asymmetric) motions of the nuclei.