Product energy distributions from ethylene photodissociation at 193 nm: a DFT direct classical trajectory study

The photodissociation of ethylene at 193 nm was studied by a B3LYP/6-31G(d) direct trajectory method, in which the trajectories were initialized from the two exit barriers associated to molecular hydrogen formation. The calculated translational energies and the H2 rotational and vibrational states distributions are in good agreement with the experimental data. Our results, together with those obtained in a previous trajectory study [A. Peña-Gallego, E. Martı́nez-Núñez, S.A. Vázquez, Chem. Phys. Lett. 353 (2002) 418], are in line with the conclusion that the dissociation dynamics is statistical in the reactant phase space, although the product energy distributions for both channels are nonstatistical.