Study On Dynamics Of LiH₂ System

In the past ten years,a large number of kinetic studies have been carried out on the LiH₂molecular system,especially the collision reaction kinetics,hydrogen extraction and displacement and its isotope substitution reaction.LiH₂ system has attracted much attention due to the important role played by LiH molecule and its free radical cation LiH⁺in cosmological chemistry,and the low number of electrons and rich kinetic properties.In order to further clarify the debate and uncertainty about the existence of barriers and wells on the reaction channel and to explore the rich dynamic properties of LiH₂ molecular system in more detail,our group calculated the multi-reference configuration interaction method in the early stage.A large number of energy points are calculated from the beginning,and the base group extrapolation model is used to extrapolate them to the complete basis set to construct a high-precision full-wiki potential energy surface?Li-PES?.Based on this potential energy surface,we conducted theoretical studies including the effects of vibration excitation,rotational excitation,and isotope effects on the dynamics of the system.However,the dynamic properties of H+LiH and D+LiD have not been studied based on the new potential energy surface.In order to enrich the related dynamic properties of the system based on the new potential energy surface,this paper carried out theoretical research and calculation on the dynamics of H+LiH and its isotope substitution D+LiD reaction based on the potential energy surface?Li-PES?constructed by our team and the potential energy surface?Chen-PES?constructed by Chen et al.This article mainly includes two parts,one is the theoretical part,including the basic theory of potential energy surface and the basic theory of dynamics,mainly the first two chapters of the article;the second is the dynamics research part of the system,which mainly includes the research of the system.Background,ground state,the kinetic effects of the collision energy on the reaction,the vibrational excitation and the isotope effect on the kinetics of the reaction,the development process of the system is introduced firstly.It is pointed out that the significance of our research on the system is to enrich the dynamic properties of the system based on Chen-PES and Li-PES,and to compare the similarities and differences between the two faces.Then we performed quasi-classical trajectory calculations on both faces of Li-PES and Chen-PES in the energy range of 0-30 kcal/mol,and selected100000 trajectories for each kinetic energy to simulate dynamics.Then the effects of vibration excitation?v=0,1,2,3,j=0?and rotational excitation?v=0,j=10,20,30?and isotope D+LiD on the kinetics of the system were studied.It was found that the reaction is more likely to occur at low collision energies,and the vibrational excitation and isotope effects have an inhibitory effect on the occurrence of the reaction.In the fourth chapter,the results are summarized and prospected.