CnBδ(δ=0, ±1; n =1～6)团簇的结构、稳定性和光谱

采用密度泛函理论(DFT)的B3LYP方法,在6-31G*和6-311＋G(3df)水平上对C_nB(n=1～6)团簇及其阴离子和阳离子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C_nB(n=1～6)团簇的电离能,绝热电子亲合势以及C_nB^δ(δ=0,±1)团簇的能隙.结果表明C_nB^－(n=1～6)团簇的基态构型均为线形,这与等电子的C_n簇合物的结构是一致的; C_nB(n=1～6)团簇的基态构型中,除C₂B为不对称的三角形,C₆B为具有C_2v对称性的环状结构外,其余均为线形结构.阳离子团簇中n=2、3、6的基态结构具有C_2v对称性外,其它几个均为线形结构.从几何参数和振动频率上发现,采用密度泛函B3LYP方法在6-311＋G(3df)和6-31G*两种基组上计算得到的键长参数和振动频率非常接近,说明B3LYP方法在计算C_nB簇合物结构参数上对于基组的选择是不太敏感的.通过对C_nB(n=1～6)的光电子能谱性质的研究发现,C₄B容易获得一个电子形成阴离子团簇,但失去一个电子是很困难的,这与实验上观测到的结果非常吻合.

Structure,Stability and Spectra of CnBδ (δ=0,± 1;n=1～ 6) Clusters

Using density functional theory associated with B3LYP method with 6-31G* and 6-311＋G(3df) basis sets, the optimization of the geometries and electronic structures and the calculation of frequencies for C_nB^δ(δ=0,±1; n=1～6) clusters have been carried out. In addition, the detachment energy ,adiabatic electron affinities of CnB and energy gap of C_nB^δ(δ=0, ±1) were obtained. The results show that the ground state structures of C_nB^－(n=1～6) clusters are linear as C_n clusters due to their isoelectrons. For C_nB (n=1～6) clusters, the ground state structure of C₂B is asymmetric triangle and C₆B is C_2v symmetry planar monocycle, while the other clusters are linear.C₂B^＋ ,C₃B^＋and C₆B^＋ are C_2v symmetry in C_nB＋(n=1～6) clusters. From the geometrical parameters and vibrational frequencies of boron-carbon clusters from 6-311＋G(3df) and 6-31G* basis sets, it was found that the B3LYP functional is less sensitive to the selection of the basis set in investigating the boron-carbon clusters. The photoelectron spectrum of C_nB(n=1～6) clusters indicates that C₄B is easy to accept one electron and difficult to lose one electron, which is in good agreement with the experimental result.