Potential energy surfaces for singlet and triplet states of the LiH2+ system and quasi-classical trajectory cross sections for H + LiH+ and H+ + LiH

Abstract

A new set of six accurate ab initio potential energy surfaces (PESs) is presented for the first three singlet and triplet states of LiH₂⁺ (1,2¹A', 1¹A'', 1,2³A', and 1³A'' states, where four of them are investigated for the first time), which have allowed new detailed studies gaining a global view on this interesting system. These states are relevant for the study of the most important reactions of lithium chemistry in the early universe. More than 45 000 energy points were calculated using the multi-reference configuration interaction level of theory using explicitly correlated methods (ic-MRCI-F12), and the results obtained for each individual electronic state were fitted to an analytical function. Using quasiclassical trajectories and considering the initial diatomic fragment in the ground rovibrational state, we have determined the integral cross sections for the H + LiH⁺(X²Σ⁺, C²Π) and H⁺ + LiH(X¹Σ⁺, B¹Π) reactions. In these calculations all available reaction channels were considered: the chemically most important H or H⁺ transfer/abstraction as well as atom exchange and collision induced dissociation for up to 1.0 eV of collision energy.