双金属AunCu0- (n=1~9) 团簇结构、稳定性、电子及光学性能研究

为了探究铜掺杂金团簇的结构及特性,依据密度泛函理论对Au_nCu^{0/-(n=1~9)团簇的结构、稳定性、电子及光学性能进行了系统分析。基于卡利普索结构预测程序,在B3LYP/Lanl2dz水平下优化得到了不同尺寸的基态结构。研究表明,除Au₇Cu和Au₈Cu-呈现三维结构外,其它尺寸下的基态均呈现二维平面结构。而且,Au_nCu0/-的基态可通过在Aun-1Cu0/-}基态基础上添加一个Au原子得到。稳定性分析确定了Au₅Cu和Au₂Cu-团簇在各自体系中拥有相对强的稳定性。磁性分析发现,闭壳层电子结构体系的总自旋磁矩为零；开壳层电子结构体系分别具有1 μB的总磁矩。分析极化率表明,Au₉Cu和Au₉Cu-团簇对外场的各向异性响应最强,AuCu和Au₃Cu-团簇对外场的各向异性响应最弱。AdNDP分析发现,众多σ键连通了整个分子骨架,促进了整个团簇的稳定。基于Multiwfn程序,拟合的光电子能谱、红外谱、拉曼谱和紫外可见光谱可为实验上鉴别Au_nCu^0/-团簇的结构提供帮助。

Study on structures, stabilities, electronic and spectral properties of gold-copper bimetallic AunCu0-(n=1-9) clusters

In order to explore the structures and properties of copper-doped gold clusters, the structures, stabilities, electronic and spectral properties of bimetallic Au_nCu^0/- (n=1-9) clusters were systematically analyzed according to the density functional theory. The lowest energy structrues were obtained at the B3LYP/Lanl2dz level based on the CALYPSO searching method. The results show that except for the three-dimensional structures for Au₇Cu and Au₈Cu-, the lowest energy structures favor two-dimensional structures. Moreover, Au_nCu^0/- clusters can be obtained by adding one Au atom on the lowest energy structures of Aun-1Cu^0/-. The stability studies indicated that Au₅Cu and Au₂Cu- have relatively strong stability in neutral and anionic serises, respectively. Magnetic properties analyses revealed the total magnetic moments of the closed shell systems are zero; the total magnetic moments keep a constant 1 μB for opened shell systems. The analyses of polarisability revealed that Au₉Cu and Au₉Cu- clusters have relativley stronger anisotropic response to the external field, while AuCu and Au₃Cu- clusters have relativley weaker anisotropic response to the external field. According to AdNDP analysis, the molecular shape is connected by σ-bonds, which contribute to the stability of doped systems. Based on the Multiwfn program, the photoelectron spectra, infrared spectra, Raman specta and UV-vis spectra were simulated and could help to identify the structures of Au_nCu^0/- clusters in experiments.