Quasi-classical trajectory study of the S + OH → SO + H reaction: from reaction probability to thermal rate constant

Abstract

First quasi-classical trajectory calculations have been carried out for the S(³P) + OH(X ²Π) → SO(X ³Σ⁻) + H(²S) reaction on an ab initio global potential energy surface for the ground electronic state, X ²A′′, of HSO. Cross sections, computed for collision energies up to 1 eV, show no energy threshold and decrease with the increasing collision energy. Rate constants have been calculated in the 5–500 K temperature range. The thermal rate constant is in good agreement with approximate quantum results, while a disagreement is found at 298 K with the experimental data. Product energy distributions have also been reported at four collision energies from 0.001 to 0.5 eV. The shapes of the rovibrational and angular distributions suggest the formation of an intermediate complex that is more and more long-lived as the collision energy increases.