CoB_n(n≤19)团簇结构、电子性质和磁性的密度泛函理论研究  

Structures,electronic properties and magnetisms of CoB_n(n≤19) clusters:density functional theory investigations

作　　者：刘火雁[1] 雷雪玲[1] 刘志锋[1] 刘立仁[1] 祝恒江[1] 

机构地区：[1]新疆师范大学物理与电子工程学院,乌鲁木齐830054

出　　处：《原子与分子物理学报》2012年第1期56-66,共11页Journal of Atomic and Molecular Physics

基　　金：新疆师范大学优先发展学科基金;自治区高校科研计划重点项目(XJEDU2009127);国家自然科学基金(10964012)

摘　　要：采用密度泛函理论中的广义梯度近似(Generalized Gradient Approximation,GGA)方法,对不同自旋多重度的CoB_n(n≤19)团簇的平衡几何结构、电子性质和磁性进行了研究.表明结果随着尺寸的增加,CoB_n(n≤19)团簇最低能量结构从平面结构逐步演变为立体结构,Co从主团簇的外部向内部转移.团簇最低能量结构的二阶能量差分表明CoB_3、CoB_7、CoB_(10)、CoB_(12)、CoB_(14)和CoB_(16)团簇较相邻团簇稳定.Co的掺杂增强了硼团簇的化学活性.最低能量结构中Co的d轨道和B的p轨道存在着明显的杂化.当n<13,Co处于主团簇的外部时,Co的带电量为正,Co具有磁矩.当n≥13,Co处于主团簇的内部时,Co的带电量为负,Co的磁矩几乎为零.团簇最低能量结构的总磁矩主要来自Co的3d轨道的贡献,且总磁矩随团簇尺寸增大呈现奇偶振荡.The equilibrium structures, electronic properties and magnetisms of CoBn（n≤19） clusters have been investigated by generalized gradient approximation （GGA） of density functional theory at different spin multiplicities. The lowest energy structures of CoBn（n≤19） clusters,with the size increasing, have gradually evolved from planar shape to cubic structure and the site of Co transfers from the main clusters＇ outer surface to inner direction. The second-order energy differences of the lowest energy structures show that CoB3, CoB7, CoB10, CoB12, CoB14 and CoB16 clusters possess relatively higher stabilities. The strong hybridization between the d orbital of Fe and the p orbital of B for the lowest energy clusters. For n〈13, the Co atom locates in the peripheral position of the main cluster, with positive electrical charges and magnetic moment, whereas with negative ones for n≥13 when the Co atom transfers into the inner part of the cluster and its magnetic moment almost disappears. The total magnetic moment for the lowest energy cluster is mainly provided by 3d orbital of Co atom, and exhibits the odd-even oscillation tendency with the increasing of cluster size.

关 键 词：CoBn团簇 最低能量结构 密度泛函理论 磁性 

分 类 号：O561[理学—原子与分子物理]