| With the dearth of petroleum resources and constantly deteriorating ecological environment, find and develop new energy source become a hot topic all over the world. Hydrogen energy as a new energy source, has been accepted during the process of new energy source's find. However, the application of energy source is limited by its storage, and the alkali metal compounds which have a vast storage of hydride become a research key point. The big particles of solid are hardly adequate reaction during the reaction. Alkali metals compounds Clusters with small particles, which make the reaction can be carried through easily. The reaction mechanism of alkali metal compounds Clusters and hydrogen is paid more and more attention, and the study about this is limited now. In this paper, by means of the density functional theory (B3LYP) methods,the reaction between Li3N and H2, (Li3N)2 and H2 have been calculated and analysis basing on the 6-311G*.In the first chapter, the advantages and the current situation of store materials of hydrogen energy has been introduced, which include carbon materials, metal- organic matter frame materials, metal alloy material, alkalis nitride and so on. Furthermore, it is emphatically introduced about the merits of Li-N-H set metal clathrate hydrogen storage material and alkalis nitride.In chapter 2, the evolution of quantum chemistry and the research method about apply quantum chemistry to cluster were summarized, and the transition state theory and intrinsic coordinate theory were introduced.Micromechanism of the reaction between Li3N and H2 has been studied in chapter 3. The formula of the reaction is Li3N+2H2 -Li2NH +LiH + H2-LiNH2 + 2LiH. The geometric model of the reactions, intermediate, transition-state and products had been optimized at the same time. The correctness of intermediate and transition-state has been confirmed by the results of vibrational analysis. The pathway was calculated by IRC which has been affirmed as single channel and exothermic reaction. The calculation results indicate that the activation energy of first and second step reaction are 117.3 kJ/mol and 5.5136 kJ/mol. Comparing to the first step reaction, the second step reaction is more easy, which provides a theoretical basis for the further study of the reaction between Li3N and H2.In chapter 4, Micromechanism of the reaction between (Li3N)2 Li3N and H2 has been studied. The formula of the reaction is Li3N+2H2-Li2NH +LiH + H2-LiNH2 + 2LiH. The geometric model of the reactions, intermediate, transition-state and products had been optimized at the same time. The correctness of intermediate and transition-state has been confirmed by the results of vibrational analysis. The pathway was calculated by IRC which has been affirmed as single channel and exothermic reaction. The calculation results indicate that the activation energy of first and second step reaction is 77.78 kJ/mol and 17.07 kJ/mol, and the second step reaction is easier than the first. Comparing the reaction of Li3N and H2 to the reaction of (Li3N)2 and H2,we find that the second step reaction of Li3N and H2 is the most easy one, and provides a theoretical basis for the further study of the reaction between (Li3N)2 , Li3N and H2.
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