A classical trajectory study of the F+C₂H₄→ C₂H₄F→H+C₂H₃F reaction dynamics

The Monte Carlo classical trajectory method was used to study the dynamics of F + C₂H₄ recombination and the ensuing C ₂H₄F decomposition. The trajectories were initiated at a relative translational energy of 20.0 kcal/mole with ethylene vibrating with its zero-point energy. Product energy distributions as well as velocity and angular momentum scattering angle distributions were calculated. The H + C ₂H₃F relative translational energy distribution is statistical at the exit-channel saddle point. The nonstatistical relative translational energy distribution in the products arises from the centrifugal potential at the exit-channel saddle point and the potential energy release in the exit channel, of which approximately 80% goes to relative translation. Correlation coefficients were computed between various dynamic variables and many important correlations are found, primarily between the various angular momenta and the C₂H₃F rotational energy. A particularly significant correlation is the one between H + C₂H₃F orbital angular momentum at the exit-channel saddle point and in the products. The trajectory scattering angles and the energy distributions are compared with experimental studies of the reaction dynamics. It is pointed out that the statistical H + C₂H₃F relative translational energy distribution observed at the exit-channel saddle point does not necessarily imply a statistical unimolecular lifetime distribution for the excited C ₂H₄F radicals.