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

The authors report a new single-valued potential energy surface for the ground state of HO{sub 2} 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 HO{sub 2} (DMBE IV) potential energy function, exploratory dynamics calculations of the O + OH {yields} O{sub 2} + H reaction have also been carried out by the quasiclassical trajectory method. Thermal rate coefficients are reported for T = 250, 1,250, and 2,250 K that are shown to be in good agreement with the best reported measurements.