Double many-body expansion potential energy surface for ground-state HO3

Abstract

We report a single-valued double many-body expansion potential energy surface for the ground electronic state of HO₃ which has been calibrated at short range from newly calculated ab initio energies including electron correlation. The long-range part of the potential surface includes the electrostatic energy up to four-body terms, while the dynamical correlation has been truncated at the three-body level. The main attributes of the HO₃ double many-body expansion potential energy surface have also been characterized. The latter are found to be in generally good agreement with those from the reported ab initio energies, and also with the results from previous theoretical calculations. For the H + O₃ reaction, the novel potential energy surface shows no activation barrier, while predicting a metastable HO₃ structure with respect to the separated HO + O₂ products. A quasiclassical trajectory study of the H + O₃ → HO + O₂ reaction has also been carried out, and the calculated thermal rate coefficients shown to be in good agreement with the experimentally determined values.