The photodissociation of dimethylnitrosamine studied by classical trajectories on a b i n i t i o potential energy surfaces

We have determined ab initio potential energy surfaces of the S0 and S1 states of dimethylnitrosamine, with particular care for the N–N bond dissociation pathway. The electronic correlation has been taken into account by a multireference perturbation method, CIPSI. Classical trajectories in the S1 surface have been run with statistically determined initial conditions. Computed lifetimes and orientation parameters for the recoil velocity and the NO fragment angular momentum are in agreement with experimental data. Large amplitude internal motions are of primary importance in determining such quantities.