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采用第一性原理方法研究了NH_3分子在LiH(100)晶面的表面吸附情况.通过研究LiH(100)/NH_3体系的吸附位置、吸附能和电子结构,发现NH_3分子在LiH(100)晶面主要是化学吸附,初始位置为NH_3分子中N-H键在Li顶住时失去一个H原子,并在LiH(100)面形成NH_2基,其吸附能为0.511 eV,属于强化学吸附,吸附作用最强.此时NH_2基与附近H原子和Li原子之间为离子键作用,NH_2基中N—H键为共价键;NH_3分子中另一个H原子与LiH表面的一个H原子形成一个H_2分子逸出表面.H_2分子中H-H键为明显的共价键.
The first-principle method was used to study the adsorption of NH 3 on the surface of LiH (100) crystal. The adsorption sites, adsorption energies and electronic structures of LiH (100) / NH 3 system were investigated. The surface is mainly chemisorbed. The initial position is that the NH bond in the NH 3 molecule loses one H atom when it is supported by Li, and forms NH 2 group on the LiH (100) surface. The adsorption energy is 0.511 eV, which belongs to strong chemisorption In this case, the NH_2 group is an ionic bond with the nearby H atom and the Li atom, and the N-H bond in the NH_2 group is a covalent bond. Another H atom in the NH_3 molecule forms a H_2 molecule with one H atom on the surface of LiH Escape from the surface.HH molecule HH bond is obvious covalent bond.