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 + NH(3) 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 ( approximately 50%) with the H(2) diatomic product being vibrationally cold (v' = 0, 1). The vibrational distribution of the triatomic NH(2) product shows that it is mostly found in its vibrational ground state (approximately 80%), with a small vibrational excitation in the bending mode (approximately 12%). This distribution varies little with the collision energy. The product angular distribution shows sideways-backward behavior at low energies, shifting the scattering toward the sideways hemisphere when the energy increases. The effect of the zero-point energy constraint on these dynamical properties was analyzed.