Rate constant for OH (Π2) +O (P3) →h (S2) + O2 (g-3) reaction on an improved ab initio potential energy surface and implications for the interstellar oxygen problem

Abstract

The authors report a global potential energy surface for the ground electronic state of H O2 (X̃ A″2), which improves upon the XXZLG potential [Xu and, J. Chem. Phys. 122, 244305 (2005)] with additional high-level ab initio points for the long-range interaction potential in the O+OH channel. Exact J=0 quantum mechanical reaction probabilities were calculated on the new potential and the rate constant for the title reaction was obtained using a J -shifting method. The calculated rate constant is in good agreement with available experimental values and our results predict a significantly lower rate at temperature range below 30 K, offering a possible explanation for the "interstellar oxygen problem." © 2007 American Institute of Physics.