Dynamical effects in unimolecular decomposition: A classical trajectory study of the dissociation of C2H6

The unimolecular dissociation of ethane via C–C and C–H scission has been simulated by trajectory calculation on a realistic and well coupled potential energy surface. Detailed lifetime distributions were obtained from this calculation for both C–C and C–H fragmentation channels at several energies (180, 210, and 240 kcal/mole) and for several energization patterns. The potential surface was also used to determine vibrational frequencies for the activated molecular model and various critical configurations. These frequencies were applied in the accurate census of phase space volumes for precisely tailored RRKM calculations. The trajectory results for the different energization patterns do not agree with corresponding statistical predictions nor with each other. The details of these deviations are discussed with regard to the importance of dynamical effects in intramolecular relaxation and unimolecular dissociation.