(MgC)n(n=1~10)团簇电偶极矩和极化率的理论研究

Theoretical Study on Electric Dipole Moments and Polarizabilities of(MgC)n(n=[STHZ]1,2,…,10)Clusters[STBZ]

在密度泛函理论的基础上使用有限电场方法,对(MgC)n(n=1~10)团簇的电偶极矩和极化率进行系统计算.结果显示,随着尺寸的增加,(MgC)n(n=1~10)团簇的电偶极矩与能隙值呈现相反的变化趋势,结构相对长度与平均极化率表现出相似的演化行为,但与能隙值的趋势相反,且具有较高对称性的团簇结构呈现极小的电偶极矩.同时,对极化率各向异性的研究中还发现(MgC)n(n=1~10)团簇中碳原子链相对长度和碳原子电荷占据对极化率各向异性的贡献占主要部分.

The evolution of electric dipole moments and polarizabilities of(MgC)n(n=1,2,…,10)clusters have been studied by using finite electric field method based on density functional theory(DFT).The results show that energy gaps and electric dipole moments of(MgC)n(n=1,2,…,10)clusters exhibit opposite trend as the cluster size increase,and the small electric dipole moments correspond to wide energy gaps.Meanwhile,the relative structure length displays similar pattern with average polarizabilities,but show contrary trend to energy gap.These conclusions demonstrate that the electric dipole moments and polarizabilities are contributed by the geometrical and electric structures of clusters.At the same time,the investigation of polarizability anisotropy of(MgC)n(n=1,2,…,10)clusters reveals that the main contributes to polarizability anisotropy have been shown to be the relative length of carbon chain and the average charges of carbon atoms.