A Globally Accurate Neural Network Potential Energy Surface and Quantum Dynamics Studies on Be⁺(²S) + H₂/D₂ → BeH⁺/BeD⁺ + H/D Reactions

Chemical reactions between Be⁺ ions and H₂ molecules have significance in the fields of ultracold chemistry and astrophysics, but the corresponding dynamics studies on the ground-state reaction have not been reported because of the lack of a global potential energy surface (PES). Herein, a globally accurate ground-state BeH₂⁺ PES is constructed using the neural network model based on 18,657 ab initio points calculated by the multi-reference configuration interaction method with the aug-cc-PVQZ basis set. On the newly constructed PES, the state-to-state quantum dynamics calculations of the Be⁺(²S) + H₂(v₀ = 0; j₀ = 0) and Be⁺(²S) + D₂(v₀ = 0; j₀ = 0) reactions are performed using the time-dependent wave packet method. The calculated results suggest that the two reactions are dominated by the complex-forming mechanism and the direct abstraction process at relatively low and high collision energies, respectively, and the isotope substitution has little effect on the reaction dynamics characteristics. The new PES can be used to further study the reaction dynamics of the BeH₂⁺ system, such as the effects of rovibrational excitations and alignment of reactant molecules, and the present dynamics data could provide an important reference for further experimental studies at a finer level.