Si_(10)团簇成键条件和解离行为的密度泛函紧束缚研究

Investigation on bonding conditions and fragmentation behaviors of a Si_(10) cluster by density functional tight binding(DFTB)simulations

本研究利用遗传算法和基于密度泛函理论的紧束缚方法相结合的计算方法,研究了Si_(10)团簇的原子堆积结构的成键条件和电子性质.计算结果发现,Si_(10)团簇的最低能稳定结构表现为以一个三棱柱体为基础结构单元,在其3个侧面和一个底面堆积了四个金字塔堆积结构,形成了由四个金字塔包围三棱柱体的类球形结构.原子间成键强烈依赖于团簇中各原子紧邻原子的几何排布情况,原子间交叠电子布居数具有显著的方向性,随着键长增加迅速减小.由团簇中各原子成键条件的分析,可以判断Si_(7)团簇是Si_(10)团簇最容易形成的解离产物,然后出现的是Si_(6)团簇.

In this study,the bonding conditions and electronic properties of atomic stacking structure of Si_(10) clusters are studied by using the method of genetic algorithms(GAs)and density functional tight binding(DFTB)method.The calculation results show that the lowest energy stable structure of the Si_(10) cluster is represented by a triangular prism as the basic structural unit,with four pyramid stacks structure on three sides and one bottom surface,forming a spherical structure of triangular prism surrounded by four pyramids.The results demonstrate a strong dependence of the bonding in these atoms of this cluster not only on the geometric position but also on the overlap population.The overlap populations present discrete features,and decrease rapidly with the increase of the bond length.By the bonding analysis,the most likely fragmenting product is Si_(7),and then Si_(6).