The adsorption of H₂ on two kinds of Li₃N(100) crystal surfaces has been studied by the first principles. It is found that chemical adsorption mainly happens when H₂ molecules are on the Li₃N(100) crystal surfaces, but physical adsorption may also happen, which is based on the studying of the adsorption sites, adsorption energy and electronic structure of the Li₃N(100)/H₂ systems. In the most stable structures of the absorption of the Li₃N(100) surfaces on which the atoms are Li and N, the H₂ molecules are dissociated. At last the H atoms tend to the two N top respectively, forming two NH. The adsorption energy is 5.157 eV. This process belongs to the strong chemical adsorption|while the interaction between H₂ molecule and Li₃N(100) surface is mainly due to the overlap-hybridization among H1s, N2s and N2p states, through which covalent bonds are formed between N and H atoms. In the most stable structures of the absorption of the Li₃N(100) surfaces on which the atoms are Li, and the H₂ molecules are also dissociated. The H atom tend to the hollow, and the adsorption energy is 2.464 eV. This process also belongs to the strong chemical adsorption, while the interaction between Li and H is ionic.

Key words: first principle, Li₃N(100), H₂, adsorption