A direct DFT dynamics study of the photodissociation of triplet acetaldehyde

Photodissociation of acetaldehyde at 308 nm via the radical CH3 + HCO channel has been studied on the triplet state surface by DFT classical trajectory calculations using the B3LYP/6-31G* electronic structure method. A rotational analysis of product HCO predicts a non-Boltzmann distribution and that the energy is partitioned preferentially along the b and c axes rather than axis a. Product HCO is produced with no vibration excitation but the radical CH3 is predicted to be vibrationally excited. These results corroborate the most recent LIF experiment on this reaction. When the product energies are scaled, to take into account a possible underestimation of the B3LYP/6-31G* reverse barrier height, the resulting energies are in excellent agreement with experiment.