Classical trajectory studies of the unimolecular decomposition of the 2-chloroethyl radical

Classical trajectories have been employed in a study of the intramolecular dynamics and unimolecular decomposition of the 2-chloroethyl radical. A potential-energy surface was constructed by using the available experimental data and theoretical results. The following reaction channels were included in the study: ⋅CH2CH2Cl→CH2=CH2+⋅Cl, ⋅CH2CH2Cl→CH2=CHCl+⋅H. Mode-specific behavior was investigated by computing ensembles of trajectories for initial conditions (1) in which the normal-mode vibrations of the radical were assigned zero-point energies and a single C–H local stretch on the radical end of the system was excited, and (2) in which the normal modes were all excited so as to distribute the total energy uniformly throughout the radical. First-order rate coefficients were calculated both for the disappearance of the reactant and for the two chemically distinct reaction channels. The results do not indicate significant, if any, mode-specific effects. Energy transfer from and into local C–H stretching modes was studied. Relaxation of an initially excited C–H bond is observed to be irreversible and complete within about 0.6 ps.