Effect of SiO⁺ Rotational Excitation on Dynamics of SiO⁺ + H₂ → SiOH⁺ + H Reaction

Quasi-classical trajectory calculations and quantitative trajectory classification using DBSCAN and K-NN algorithms have been employed to study the specifics of the significant promotion of the SiO⁺ + H₂ reaction by high rotational excitation of SiO⁺. There are three different reaction pathways identified. Path-I is a direct reaction process in which the product is formed when H₂ collides with the O atom side of SiO⁺ and the H-H bond breaks. H₂ first collides with the Si atom in path-II, then bounces back, and encounters the O atom to complete the reaction. Path-III is characterized by the formation of an HSiOH⁺ complex, is less affected by rotational excitation, and has the smallest contribution to the entire reaction. At low collision energies, rotational excitation slightly promotes the reaction, possibly due to the coupling of the rotational mode of SiO⁺ and the reaction coordinate of the submerged saddle point. However, this effect weakens with increasing rotational excitation, leading to a complex change in the total integral cross section. Among them, only path-I shows increased reactivity at high rotational excitation. At high collision energies, the integral cross section of the reaction is less sensitive to the rotational quantum number of the reactant, and only a slight increase is observed at the high rotational excitation of SiO⁺.