Global potential energy surface, vibrational spectrum, and reaction dynamics of the first excited (? A2 ′) state of HO_2

摘要

The authors report extensive high-level ab initio studies of the first excited (? A2 ′) state of HO_2. A global potential energy surface (PES) was developed by spline-fitting 17 000 ab initio points at the internal contracted multireference configuration interaction (icMRCI) level with the AVQZ basis set. To ascertain the spectroscopic accuracy of the PES, the near-equilibrium region of the molecule was also investigated using three interpolating moving least-squares-based PESs employing dynamically weighted icMRCI methods in the complete basis set limit. Vibrational energy levels on all four surfaces agree well with each other and a new assignment of some vibrational features is proposed. In addition, the dynamics of both the forward and reverse directions of the H+ O_2 (? Δ1_g) OH+O reaction (J=0) were studied using an exact wave packet method. The reactions are found to be dominated by sharp resonances.