Potential Energy Surfaces for the First Two Lowest-Lying Electronic States of the LiH₂⁺ System, and Dynamics of the H⁺ + LiH ⇌ H₂⁺ + Li + Reactions

Two new potential energy surfaces are established for the ground and first excited electronic states of the LiH₂⁺ system, which are important for the astrophysics-related H⁺ + LiH⁺ and H⁺ + LiH reactions. The ab initio energy points are calculated using the complete active space self-consistent field and multireference configuration interaction method with aug-cc-pVQZ basis set. At each state, more than 40000 energy points are calculated. The spectroscopic constants of the diatoms and the topographical characters of the new surfaces are examined in detail, showing good agreement with the available literature results. The reaction probabilities, integral and differential cross sections, and rate constants for the H⁺ + LiH ⇌ H₂⁺ + Li reactions are obtained by performing quantum dynamics calculations, and compared with the previous literature results. The reaction mechanisms are discussed in detail. It is shown that the new surfaces can be recommended for the dynamics study of the H⁺ + LiH⁺ and H⁺ + LiH⁺ reactions and other research including LiH₂⁺ based rovibrational spectra and cluster dynamics.