Cold H + O2 collisions: Impact of resonances, geometric phase, and alignment

We report a quantum mechanical investigation of cold inelastic collisions between H and O2 (Ec ≤ 10 K) using a recently developed diabatic potential energy matrix for the lowest two 2A″ states coupled by conical intersections. Time-independent close coupling calculations were carried out in both the adiabatic and nonadiabatic representations in order to delineate the impact of the geometric phase (GP) on scattering. Both adiabatic and nonadiabatic results show many resonance peaks dominated by single partial waves. The inclusion of GP is found to have a large impact on the scattering resonances and more generally on both the integral cross section (ICS) and differential cross section (DCS). In addition, our investigations show that both ICS and DCS could be controlled by the initial alignment of O2, and the effect of the GP also manifest in the stereodynamics of the H + O2 collisions.