Quasi-classical Trajectory Study of F+H₂O→HF+OH Reaction: Influence of Barrier Height, Reactant Rotational Excitation, and Isotopic Substitution (cited: 4)

The reaction dynamics of the F+H₂O/D₂O→HF/DF+OH/OD are investigated on an ac-curate potential energy surface (PES) using a quasi-classical trajectory method. For bothisotopomers, the hydrogen/deuterium abstraction reaction is dominated by a direct rebound mechanism over a very low “reactant-like” barrier, which leads to a vibrationally hot HF/DF product with an internally cold OH/OD companion. It is shown that the lowered reaction barrier on this PES, as suggested by high-level ab initio calculations, leads to a much better agreement with the experimental reaction cross section, but has little impact on the product state distributions and mode selectivity. Our results further indicate that rotational exci-tation of the H₂O reactant leads to significant enhancement of the reactivity, suggesting a strong coupling with the reaction coordinate.