摘要:
利用密度泛函理论在B3LYP/6-311G＊水平上对叠氮化合物（HMgN3）n（n=1—5）团簇各种可能构型进行了几何优化,预测了各团簇的最稳定结构.并对最稳定结构的成键特性、电荷分布、振动特性及稳定性进行理论研究.结果表明：HMgN3团簇最稳定结构为直线型;（HMgN3）n（n=2,5）团簇最稳定结构为叠氮基中N原子和金属原子相连构成Mg—N—Mg结构;（HMgN3）n（n=3,4）团簇最稳定结构为叠氮基与Mg原子相互链接形成的环状结构.团簇最稳定结构中金属Mg原子均显示正电性,H原子均显示负电性,叠氮基中间的N原子显示正电性、两端的N原子显示负电性,且与Mg原子直接作用的N原子负电性更强.Mg—N键和Mg—H键为典型的离子键,叠氮基内N原子之间是共价键.团簇最稳定结构的红外光谱分为三部分,其最强振动峰均位于2258—2347cm-1,振动模式为叠氮基中N—N键的反对称伸缩振动.叠氮基在团簇和晶体中结构不变,始终以直线型存在.稳定性分析显示,（HMgN3）3团簇相对于其他团簇更为稳定.
Abstract:
We optimize the possible geometrical cluster structures and predicte relative stability of （HMgN3）n（n=1—5） by using the hybrid density functional theory （B3LYP） with 6-311G basis sets.And the most stable isomers of （HMgN3）n（n=1—5） clusters,the bond properties,charge distributions,vibrational properties,and stability are analyzed theoretically.The calculated results show that the most stable HMgN3 has a linear structure,the （HMgN）n（n=2,5） clusters have the most stable structures in which an N atom in a sub-system and metal atom in another sub-system constitute an Mg—N—Mg structure.And the most stable structures of （HMgN3）n（n=3,4） clusters are the chain structures in which the nitrogen cardinal extremity position N atom and the Mg atom form a ring structure;the metal Mg atoms in the most stable structure show charge positivity,and H atom show charge negativity.The middle N atoms of azido show charge positivity,the N atoms on both sides of azido show charge negativity;what＇s more,the N atoms influenced by Mg atoms directly show a more charge negativity.Mg—N bond and Mg—H bond are the typical ionic bond;the bond between N atoms in azido is the covalent bond.The infrared spectra of the most optimized （HMgN3）n（n=1—5） clusters have three vibrational sections,the strongest vibrational peak lies in 2258—2347 cm-1,and the vibrational mode is anti-symmetric stretching vibration of N—N bonds in azido.Analysis of stability shows that （HMgN3）3 clusters are more stable than other clusters.
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