Nonadiabatic dynamics studies of the H( 2 S) + RbH(X 1 Σ + ) reaction: based on new diabatic potential energy surfaces.

The global diabatic potential energy surfaces (PESs) that correspond to the ground (1 2 A') and first excited states (2 2 A') of the RbH 2 system PES are constructed based on 17 786 ab initio points. The neural network method is used to fit the PESs and the topographic features of the new diabatic PESs are discussed in detail. Based on the newly constructed diabatic PESs, the dynamics calculations of the H( 2 S) + RbH(X 1 Σ + ) → Rb(5 2 S) + H 2 (X 1 Σ g + )/Rb(5 2 P) + H 2 (X 1 Σ g + ) reactions are performed using the time-dependent wave packet method. The dynamics properties of these two channels such as the reaction probabilities, integral cross sections, and differential cross sections (DCSs) are calculated at state-to-state level of theory. The nonadiabatic effects are discussed in detail, and the results indicate that the adiabatic results are overestimated from the dynamics values. The DCSs of these two channels are forward biased, which indicates that the abstraction mechanism plays a dominant role in the reaction.