B_n(n=2-8)团簇结构和稳定性的密度泛函理论研究

Density functional theory study on structure and stability of B_n( n = 2- 8) clusters

本文采用密度泛函理论(DFT)中的B3LYP方法,在6-31G*水平上对Bn(n=2-8)团簇的各种可能的几何构型和电子结构进行了优化和振动频率计算,得到了多个平衡构型.结果表明,Bn微团簇的稳定结构大部分为平面结构,只有极少数立体结构属于基态稳定结构.平面结构又分为链状和环状结构两种,链状结构的所有原子均处于同一平面,而且处于链状结构两端的键长稍短,原子向内部收缩.环状稳定结构都是一个n元环中心有一个配位的硼原子.通过对基态结构的平均原子结合能和能量二次差分的计算,得到n为奇数时团簇较为稳定.

Density Functional Theory (DFT) with B3LYP method at 6-31G*level was used to study the geom-etries and vibrational frequencies of Bn ( n=2-8) clusters.Our results showed that most structures of Bn micro-clusters are planar forms, only a handful of three-dimensional structures are stable ground state structures. Planar configurations contain chain-like and ring-like forms.The chain-like structure is that all atoms are in same planar, and bonds of chain’ s ends are short than middle’ s.All of ring-like stable structures are n-1 atoms a-round one atom in a circle.It that the clusters of n as odd number are more stable than others is found by calcu-lating an average of the ground state binding energy of atoms and the second difference.