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运用密度泛函理论(DFT)中的杂化密度泛函B3LYP方法在6-311G*基组水平上对Mg_3N_2H_m(m=1~4)和(Mg_3N_2)_nH_m(n=2~4,m=1~2)团簇的可能几何结构进行优化,预测了其最稳定结构,并对最稳定结构的电子结构,成键特性,电荷分布,振动特性及稳定性等进行分析。结果表明:当团簇吸附H原子少于N原子数目时,一般形成-NH基;随着团簇吸附H原子数目的增加,当所有N原子吸H形成-NH基后,才有-NH基吸附H原子形成-NH_2基;但并不是所有-NH基全部形成-NH_2基的饱和结构,此时部分H原子会吸附于Mg原子上形成MgH结构。H原子易吸附于凸出的、包含孤对电子的N原子上;由于孤对电子间的排斥作用,H原子的吸附位置呈相互远离趋势。团簇中N-H之间是共价键作用,而Mg-H间是离子键作用,-NH和-NH_2基在团簇中保持完整性,团簇可以很好地描述晶体的储氢行为。
(N = 2 ~ 4, m = 1) for Mg_3N_2H_m (m = 1 ~ 4) and (Mg_3N_2) _nH_m at the level of 6-311G * basis set by hybrid density functional theory B3LYP in density functional theory (DFT) ~ 2) clusters were optimized, the most stable structures were predicted, and the electronic structure, bonding properties, charge distribution, vibration characteristics and stability of the most stable structure were analyzed. The results showed that -NH groups were formed when the number of H atoms adsorbed by the cluster was less than the number of N atoms. As the number of H atoms adsorbed by the clusters increased, Adsorption of H atoms to form -NH_2 groups; however, not all -NH groups form a saturated structure of -NH_2 groups. At this time, some H atoms will be adsorbed on Mg atoms to form a MgH structure. H atoms are easily adsorbed on the protruding N atoms containing lone pairs of electrons. Due to the repulsion between lone pairs of electrons, the adsorption positions of H atoms are away from each other. N-H in the cluster is a covalent bond, while Mg-H is an ionic bond. -NH and -NH_2 groups remain intact in the cluster, and the cluster can well describe the hydrogen storage behavior of the crystal.