Quasi-Classical Trajectory Calculations of the Hydrogen Abstraction Reaction H + NH3

On a new potential energy surface (PES-2009) recently developed by our group describing the H + NH3 hydrogen abstraction reaction, we perform an exhaustive state-to-state dynamics study using quasi-classical trajectory (QCT) calculations at collision energies between 15 and 50 kcal mol(-1). The reaction cross section is very small, corresponding, to a large barrier height and reproducing other theoretical measurements. Most of the available energy appears as product translational energy (similar to 50%) with the H-2 diatomic product being vibrationally cold (nu' = 0, 1). The vibrational distribution of the triatomic NH2 product shows that it is mostly found in its vibrational ground state (similar to 80%). with a small vibrational excitation in the bending mode (similar to 12%). This distribution varies little with the collision energy. The product angular distribution shows sideways backward behavior at low energies, shining the scattering toward the sideways hemisphere when the energy increases. The effect of the zero-point energy constraint on these dynamical properties was analyzed.