Recalibration of a single-valued double many-body expansion potential energy surface for ground-state hydroperoxy and dynamics calculations for the oxygen atom + hydroxyl .fwdarw. oxygen + hydrogen atom reaction

Abstract

We report a new single-valued potential energy surface for the ground state of H02 from the double many-body expansion (DMBE) method. This new surface conforms with the three-body energy of recent ab initio CAS SCF/CCI calculations semiempirically corrected by the DMBE-SEC method and reproduces the most accurate estimates of the experimental dissociation energy, equilibrium geometry, and quadratic force constants for the hydroperoxyl radical. Using this new H02 (DMBE IV) potential energy function, exploratory dynamics calculations of the 0 + OH - O2 + PI reaction have also been carried out by the quasiclassical trajectory method. Thermal rate coefficients are reported for T = 250, 1250, and 2250 K that are shown to be in good agreement with the best reported measurements