BnTi(n=1～12)团簇的结构,电子性质和磁性

摘要

利用密度泛函理论广义梯度近似方法得到了Bn Ti (n=1～12)团簇的基态结构,并讨论了电子性质和磁性质.结果表明,n≤5时,BnTi基态结构呈平面或准平面,n＞5时,Ti原子倾向于与较多的B原子成键而呈三维结构.由二阶能量差分得出B3Ti,B7Ti,B10Ti为幻数团簇.Mulliken布居分析显示BnTi团簇中电荷由Ti原子向近邻B原子转移且以共价键与离子键共存;除BTi磁矩为5μB外,其余团簇磁矩处于0～2μB之间;团簇总磁矩主要由Ti原子的3d轨道和个别B原子提供.B3Ti和B7Ti团簇中,B原子表现为反铁磁性.%The ground-state structures, electronic and magnetic properties of B,Ti (n=l~12) clusters are systematically studied with the generalized gradient approximation based on the density functional theory. Results reveal that the ground-state structures for the small B,Ti clusters favor planar or quasiplanar structures, while starting from n = 6, the three-dimensional structure with most Ti - B bonds dominates the growth pattern. The calculated second-order energy difference manifests that the magic numbers of stability are 3, 7, 10 for the B.Ti clusters. The results of Mulliken population analysis indicate that there is the charge transfer from Ti to B site and the coexistence of ionic and covalent bonding characteristics. The total magnetic moments of the B,Ti clusters range from 0 to 2 μB except the Bti (5μb) clusters, and are mainly provided by the 3d orbital of Ni atom and some B atoms. The magnetic moment of the B atoms in B3 Ti and B7 Ti clusters exhibits the antiferromagnetic alignment.