摘要:
采用第一性原理方法研究了H2分子在Li3N（110）晶面的表面吸附.通过研究H2/Li3N（110）体系的吸附位置、吸附能和电子结构发现：H2分子吸附在N桥位要比吸附在其他位置稳定,此时在Li3N（110）面形成两个—NH基,其吸附能为1.909eV,属于强化学吸附;H2与Li3N（110）面的相互作用主要是H1s轨道与N2s,2p轨道的重叠杂化,N与H之间形成共价键;N桥位吸附时H2分子的离解能垒为1.63eV,表明在一定热激活条件下H2分子在Li3N（110）表面会发生离解吸附;N顶位吸附时,优化结束后形成—NH2基,但吸附能为负值,即该吸附方式不稳定,可见Li3N（110）面与H2反应不易直接生成LiNH2.
Abstract:
The adsorption of H2 on a Li3N（110） crystal surface is studied by first principles.Preferred adsorption sites,adsorption energy,dissociation energy and electronic structure of the H2/Li3N（110） systems are calculated separately.It is found that H2 is adsorbed on the N bridge site more favorably than on the other sites,while two —NH radicles are formed on the Li3N（110） crystal surface.The calculated adsorption energy on the N bridge site is 1.909 eV,belonging to a strong chemical adsorption.The interaction between H2 and Li3N（110） surface is due mainly to the overlapping among H 1s,N 2s and N 2p states,through which covalent bonds are formed between N and H atoms.An activation barrier of 1.63 eV is found for the dissociation of H2 molecule in N bridge configuration,which indicates that the dissociative adsorption of H2 on Li3N（110） surface is favorable under the certain heat activation condition;—NH2 radicle is formed after the optimization of H2 adsorbed on the N top site.The adsorption energy on the N top site is negative.In other words,this adsorption is unstable.So it is concluded that it is not easy to produce the LiNH2 between Li3N（110） face and H2 directly.
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