New Ab Initio Potential Energy Surface and Quantum Product-State Resolved Reaction Dynamics Investigation for the H + F 2 Reaction

In recent years, the H + F₂ reaction has attracted much attention because of its important role in theory and in chemical lasers. The aim of this study was to report a highly accurate potential energy surface (PES) for this reaction and carry out a product-state resolved reaction dynamics study of the H + F₂ (v₀ = 0, j₀ = 0, 1, 2) → HF + F reaction in a collision energy range [0.0, 1.0] eV with the time-dependent wave packet method. The HF₂ PES was constructed using the permutation invariant polynomial neural network method with thousands of energy points calculated by the MRCI-F12+Q method with the AVTZ basis sets. The calculated results suggest that the rotational excitation of low-lying states of reactant F₂ has little effect on the reaction. The vibrational level population inversion of the product HF is significant, and the HF product is most to be produced in the v' = 4-7 vibrational states. At lower collision energy, the product HF preferred to be populated in highly excited rotational states, but at higher collision energies, the rotational distributions roughly exhibit Gaussian function distributions. The calculated reaction rate constants agree with the experiments well but with a little underestimation. This study suggests that the reaction H + F₂ is a wonderful prototype for chemical lasers, just like the more famous H₂ + F reaction, agreeing well with the previous findings.