Quantum dynamics studies on the non-adiabatic effects of H plus LiD reaction

After the Big Bang, chemical reactions of hydrogen with LiH and its isotopic variants played an important role in the late stage of recombination. Moreover, these reactions have attracted the attention of experts in the field of molecular dynamics because of its simple structure. Electronically non-adiabatic effects play a key role in many chemical reactions, while the related studies in LiH2 reactive system and its isotopic variants are not enough, so the microscopic mechanism of this system has not been fully explored. In this work, the microscopic mechanism of H + LiD reaction are performed by comparing both the adiabatic and non-adiabatic results to study the non-adiabatic effects. The reactivity of R1 (H + LiD -> Li + HD) channel is inhibited, while that of R2 (H + LiD -> D + LiH) channel is enhanced when the non-adiabatic couplings are considered. For R1 channel, a direct stripping process dominates this channel and the main reaction mechanism is not influenced by the non-adiabatic effects. For R2 channel, at relatively low collision energy, the dominance changes from a rebound process to the complex-forming mechanism when the non-adiabatic effects are considered, whereas the rebound collision approach still dominates the reaction at relatively high collision energy in both calculations. The presented results provide a basis for further detailed study on this importantly astrophysical reaction system.

Automated summary

Chemical reactions of hydrogen with LiH and its isotopic variants after the Big Bang played a crucial role in late stage recombination. The simplicity of their structure has attracted the attention of molecular dynamics experts. The non-adiabatic effects in the LiH2 reactive system and its isotopic variants have not been fully explored, hindering the microscopic understanding of this system. This study compares adiabatic and non-adiabatic results to investigate the microscopic mechanism of the H + LiD reaction, revealing the influence of non-adiabatic effects on the reaction channels.