Geometry And Electronic Structure Of Mixed Clusters Of Silicon And Zinc

The micro-mechanism, anomalous physical and chemical properties of atomic cluster have provided a way for producing and developing new material. The properties of cluster-assemble material not only depend on the size of its building block, but on the atomic and electronic structure of clusters. Therefore, a number of theoretic and experimental researches have focused on exploring such micro-mechanism as stable structures and electronic structure of clusters. Silicon is such an important material for semiconductor. Researchers found out that pure silicon cluster shows poor stability. However, by mixing some metal atoms into silicon cluster, the stability, properties of silicon cluster can be improved; new functional material can be developed. For those reasons, there is scientific significance and applied value to study semiconductors by mixing metal into silicon. This thesis has made a systematic and theoretic study on the silicon-based cluster mixed with zinc, discussed the geometric stability and electronic structural properties of the ZnSi_n (n= 1-6) clusters by the use of DFT.The first chapter of this thesis is about the overview of study on clusters, silicon and silicon-mixed clusters. The second chapter is a brief introduction to quantum mechanics. Also, the latest development of cluster study and the quantum chemistry computation in designing cluster material are discussed.In the third chapter, geometric structure and electronic property of ZriSi_n (n=1～6) clusters is investigated systemically using hybrid-density-functional theory. Geometric optimizations of ZnSi_n (n=1～6) clusters is computed at the (U) B3LYP level and the base geometric structure of ZnSi_n(n=1-6) clusters are established. Then, the most stable abruption energies in structure, natural population, natural electronic structure, Mulliken atomic net population and overlap population; HOMO-LUMO energy gap, etc. are analyzed. Study shows that D(3,2) is the largest in abruption energies in the ZnSi_n(n=1-6) clusters, ZnSi₃ clusters with self-rotating S=1/2 is the most stable in structure among ZnSi_n(n=1-6) clusters, as is similar to the structure of RhSi_n(n=1-6) cluster. Natural population study shows that Zn atom loses electrons, Si atom obtains electrons, and electrons transfer from 4s track of Zn atom and 3 s track of Si to 3p track of Si. Interactive force between Si-Si in ZnSi_n(n=1-6) clusters are greater than that between Zn-Si. By energy gap of HOMO-LUMO, it is concluded that ZnSi₃ clusters shows more chemical stability. So ZnSi₃ is the greatest in stability among ZnSi_n(n=1-6) clusters, while ZnSi₂ is the greatest in chemical forces. In the fourth chapter, it is pointed out that theoretical simulation calculation plays an important role in designing clusters and nanometer-material. Some achievements from current study, opportunities and challenges faced and plan in subsequent study in the field of cluster and nanometer-material design are also presented.