硼化合物及材料在化工、航空航天、材料等领域都具有极其广泛的应用，如超硬材料、半导体电子器件以及具有抗菌特性的生物化合物等。2015年二维硼材料—硼墨烯的成功合成又为新型硼材料的设计和发展提供了基础，开启了硼基平面材料的研究大门。而纯硼团簇的研究相比于碳团簇相对较少，这是由于硼元素缺电子特性导致的成键复杂性以及硼团簇随尺寸的增长所表现的结构多样性。团簇大小数量级一般在纳米范围，可表现出很强的量子效应，从而导致很多新现象的出现。因此，使用量化计算方法系统地研究一定尺寸硼团簇的结构特点和成键特性，对揭示独特的化学成键机理和理解硼材料的特殊性能显得尤为重要。硼的缺电子特性使硼团簇更容易被富电子金属掺杂，从而平衡电子分布、维持体系稳定性。不同种类的金属和具体掺杂形式丰富了体系的几何结构、电子结构和成键特点的多样性。本文构建了一系列不同种类金属掺杂的硼团簇结构，使用本组开发的全局最优结构搜索程序验证了热力学稳定性，采用第一性原理分子动力学手段说明了动力学稳定性，利用多种成键分析手段具体理解了体系的电子结构，并探索其在金属掺杂硼材料的潜在应用。论文主要取得了以下三方面成果：一、构筑了分别类似于碳纳米管和石墨烯结构的过渡金属掺杂硼纳米管（MnB16-，TaB20-）和硼墨烯状（CoB18-，RhB18-）硼团簇，丰富了硼团簇的结构多样性。基于密度泛函和波函数方法研究了掺杂金属与硼团簇的作用机理和体系的稳定性来源。在纳米管状结构的研究中我们提出了管状结构芳香性的概念，并刷新了化合物配位数的新纪录。金属掺杂平面硼团簇的发现为金属掺杂硼墨烯材料的合成提供了强有力的理论基础。二、研究了镧系元素掺杂硼团簇（Ln2B8）的几何和电子结构，特别对磁性质进行深入挖掘。提出了双稀土反夹心硼化物的概念，丰富了对金属硼化合物团簇及相关固体材料电子结构的认识。通过不同类型金属掺杂不仅可以平衡硼材料的电子分布，而且有望得到具有优异磁性质、光学和催化性能的新型材料。三、建立了气相化合物（Ln2B8）和六硼化镧固体材料（LnB6）在几何、电子结构和成键模式等方面的潜在联系，将固体中的几何单元抽象成稳定团簇进行研究，提供了独特的研究角度从而更加有助于深入理解两类体系的稳定性，有望为新型材料的设计提供新的设计思路。
Boron materials and boron compounds are widely used in the applications on materials, chemical industry, aerospace, medical fields, such as superhard materials, semiconductor electronic devices and biological compounds with antibacterial and antiviral properties. Boron materials demonstrate diverse structures, most of which are composed of B12 icosahedron, and have four different kinds of rhombic hexahedron for pure element phases. The successful synthesis of two-dimensional boron materials in 2015 has provided a foundation for the design and development of new boron materials and opened the door for the research on boron based two-dimensional materials. Compared with carbon, boron clusters are lack of investigations, which is due to the bonding complexity caused by electron deficiency of boron and the structural diversity of boron clusters with the growth of size. The order of magnitude of clusters is generally in the nanometer range, which can show strong quantum effect and lead to the emergence of many new phenomena. Therefore, it is crucial to systematically study the structural and the chemical bonding characteristics of size-specific boron clusters by quantum chemical calculations to reveal the unique bonding mechanism and understand the properties of boron materials.Due to the electron deficiency, boron clusters are more susceptible to be doped by electron-rich metals, so as to balance the electron distribution and maintain the stability of the system. Different types of metals and specific doping forms enrich the diversity of geometric structure, electronic structure and bonding mechanism. In this thesis, we have constructed a series of different metal-doped boron clusters. The thermodynamic stability of the structure was verified by the global minimum search program. Based on various bonding analysis methods, the electronic structure and the chemical interaction were thoroughly studied. Then, we extend the stable unitary structure to 2D or 3D to explore the potential applications in metal-doped boron materials. Three main achievements are summarized as the following content:1) Analogous with carbon nanotubes and fullerenes, the transition-metal doped boron-nanotubes (MnB16-, TaB20-) and borophene-like clusters (CoB18-,RhB18-) have been fabricated, which enrich the structural diversity of boron clusters. The chemical interaction between the doped metal and boron framework and the inherent stability of the system were investigated based on density functional theory and wave functional methods. These stable clusters with high symmetry are expected to be the unitary structures for the new metal-doped boron nanomaterials.2) Lanthanide elements generally have 4f unpaired electrons so that can be served as the dopants into boron clusters. Single lanthanide atom doping and double lanthanide atom doping have been studied successively, which has enriched the understanding of the electronic structure of metal-boron compounds and the related solid materials. Different kinds of metal dopants can not only balance the electronic distribution of boron materials, but also be expected to improve new materials with excellent magnetic, optical and catalytic properties.3) It is important to establish an efficient bridge between the gas-phase compounds and solid material for better understanding of both systems. We have proposed a rational relationship between Ln2B8 and LnB6 species on the perspectives of geometries, electronic structures and bonding patterns. It provides a unique perspective to analyze the stability for both gaseous complexes and solid-state materials.
