Ab initio classical trajectory study of H₂CO→H₂+CO dissociation

Classical trajectories for H₂CO→H₂+CO dissociation have been calculated directly from ab initio molecular orbital computations at the HF/3-21G and HF/6-31G** levels of theory, without constructing a global potential energy surface. The classical equations of motion were integrated on the local fifth-order polynomial surfaces fitted to the energies, gradients and hessians computed at the beginning and end points of each step along the trajectory. The calculated vibrational and rotational energy distributions and average impact parameter of the products are in very good agreement with experiment. The relative translational energy is higher than experiment because the barrier is overestimated at both levels of theory.