Ab initio potential energy surfaces and nonadiabatic collision dynamics in H++O2 system.

The adiabatic potential energy surfaces for the lowest five electronic states of 3A″ symmetry for the H++O2 collision system have been obtained at the multireference configuration interaction level of accuracy using Dunning’s correlation consistent polarized valence triple zeta basis set. The radial nonadiabatic coupling terms and the mixing angle between the lowest two electronic states (1 3A″ and 2 3A″), which adiabatically correlate in the asymptotic limit to H(2S)+O2+(X 2Πg) and H++O2(X 3Σg-), respectively, have been computed using ab initio procedures at the same level of accuracy to yield the corresponding quasidiabatic potential energy matrix. The computed strengths of the vibrational coupling matrix elements reflect the trend observed for inelastic vibrational excitations of O2 in the experiments at collision energy of 9.5 eV. The quantum dynamics has been preformed on the newly obtained coupled quasidiabatic potential energy surfaces under the vibrational close-coupling rotational infinite-order sudden framework at the experimental collision energy of 9.5 eV. The present theoretical results for vibrational elastic/inelastic excitations of O2 are in overall good agreement with the available experimental data obtained from the proton energy-loss spectra in molecular beam experiments [F. A. Gianturco et al., J. Phys. B 14, 667 (1981)]. The results for the complementary charge transfer processes are also presented at this collision energy. [ABSTRACT FROM AUTHOR]