硼化铝团簇Al-B_n(n=2～9)的密度泛函理论研究

Theoretical Study of Structure and Infrared Vibration Spectra about AlB_n(n=2～9) Clusters

基于密度泛函理论(Density Functional Theory,DFT),对中性硼化铝团簇AlBn(n=2～9)的几何结构、稳定性以及红外振动光谱进行了理论研究,讨论了他们的不同点及AlB4、AlB5、AlB6和AlB7的基态构型和相对稳定性.对于中性AlBn(n=2～9)基态构型,对比讨论了其失去[AlBn+(n=2～9)]和得到[AlBn-(n=2～9)]一个电子后化学键强度的变化、掺入铝原子的影响以及团簇几何结构的演化.计算结果表明:虽然掺入Al之后,团簇的稳定性差异变小,但是硼团簇和硼化铝团簇都趋向于形成平面、准平面结构以获得更大的稳定性;硼团簇的构型对硼化铝团簇的结构和稳定性起着决定性的作用;AlB3、AlB5和AlB8更稳定;红外光谱的振动模式倾向于B原子和对称性优先的趋势.

The geometry structures, stabilities and infrared vibration spectra of AIB, （n = 2- 9） Clusters were investigated based on density functional theory. The ground state structures of AIB4, AIB5, AIB6 and AIB7 clusters and their relative stabilities were discussed in detail. For the AIB,, （n= 2-9） ground states, their chemical bonds were evaluated by considering the structures, which obtain and loss one electron. The effect of doping A1 atom and the revolution of geometry structures were also discussed. It was found that the difference of stabilities becomes smaller after doping A1 atom; however, the group of B atoms still plays a dominant role in the whole cluster, especially for the stability; AIB3, AIB5 and AIB8 clusters are local stable among all the clusters studied; for infrared vibration spectra, the modes of vibration, which have higher symmetry and more B atoms involved in, are prior.