The exoergic F+CH₄ reaction as an example of peripheral dynamics

Classical trajectory computations for thermal reactants on a six-atom potential show a forward scattering component which is correlated with the HF product being formed with high vibrational excitation. These trajectories are peripheral collisions where the F atom approaches CH₄ with a high impact parameter and reaction is through a nearly collinear F-H-C configuration with a stretched F-H bond. Other trajectories are well described by a hard-sphere model whose cutoff is below the range of peripheral collisions. Comparison is made with the F+H₂ and other reactions where nearly thermoneutral channels correlate with forward scattering.