Al3团簇及其表面锂原子吸附的理论研究

基于密度泛函理论（DFT），分别对Al3和Al3Li团簇可能的几种结构进行优化和频率分析，随后对所获得的结构分别采用 Becke三参数混合泛函（B3LYP）方法和耦合簇理论CCSD（T）方法计算单点能。计算结果表明：Li原子位于Al3团簇表面桥位时，能量最高；位于顶位时，能量次之；位于洞位时团簇最稳定。结合频率分析，进一步对Li原子在Al3团簇表面的扩散行为进行了研究。研究表明，位于桥位的Li原子可能通过顶位这一过渡态向Al3团簇中心位置扩散，从而形成稳定的结构。与Al3团簇相比，Al3Li（Li原子位于洞位时）团簇中，Li原子的吸附使得Al-Al原子之间的键长增加了；铝原子也由原来的电中性转变为带负电了。

Theoretical study of bare Al3 cluster and Li adsorption on its surface

By using density functional theory, the geometry optimization and frequency analysis for bare Al3 cluster and Al3Li assemblies have been performed. The energies were calculated both with B3LYP and couple-cluster CCSD(T) methods. The calculated relative energies indicated that when Li atoms occupy the hollow sites, its corresponding clusters are most stable. Combined with the frequency analysis, the diffusion of Li atom on the surfaces of Al3 clusters has also been studied. It is found that the bridge Li atom may diffuse onto hollow site through on-top transition state. Moreover, the bare Al3 and Al3Li with hollow-site Li atom were compared. In contrast with its bare Al3 counterpart, in Al3Li, the characteristic Al-Al distances lengthened and aluminum atom were turned to be negative.