MnB_n(n=1～7)团簇的结构和磁性  

Structures and Magnetism of MnB_n (n=1～7) Clusters

作　　者：张文庆 张先富[3] 高银浩[1] 靳雪刚[1] 

机构地区：[1]河南科技学院机电学院,河南新乡453003 [2]河南大学物理与电子学院,河南开封475004 [3]永城职业学院电子工程系,河南永城476600

出　　处：《磁性材料及器件》2009年第4期15-18,共4页Journal of Magnetic Materials and Devices

基　　金：河南省教育厅科技攻关资助项目(2007480001)

摘　　要：利用密度泛函理论中的广义梯度近似对MnBn(n=1～7)团簇的结构、稳定性和磁性进行了分析。结果表明,对于n<4的MnBn团簇,Mn原子掺杂未引起主团簇Bn结构的变化;而n≥4掺杂Mn原子则使主团簇Bn结构发生变化,而且MnBn团簇的结构也由二维转向三维。比较Bn和MnBn团簇基态的平均结合能,发现Mn原子掺杂后,体系的稳定性有所减弱。综合MnBn团簇基态垂直电离势和裂化能可知,n=2和6的团簇较邻近的团簇稳定。在MnBn团簇中,MnB5磁矩最大。n=5和7的MnBn团簇总磁矩主要由Mn原子提供,而其它团簇的磁性则受Mn和B原子的共同影响。Mulliken布局分析表明MnBn团簇中Mn原子磁矩主要来自局域d电子的贡献,d电子中自旋向上和自旋向下的电子态密度的不对称性是产生Mn原子磁矩的主要原因。The structural and magnetic properties of MnB. clusters （n=1-7） have been investigated by using the generalized gradient approximation （CJGA） in density functional theory. It was found that the ground state structures of B. clusters aren＇t modified by the encapsulation of the Mn atom in the MnB. （n〈4） clusters. However, starting from n 〉 4, the strucutres of the host B. clusters are changed due to the doping of the Mn atom, and the 3-D configurations become the ground state structures for MnBn clusters （n ≥ 4 ）. Comparison in the averaged binding energy of pure boron clusters and MnB. clusters revealed that dopant of the Mn atom somewhat reduces the stability of the MnB. clusters. The calculated results on the vertical ionization potentials and the fragrnention energies indicated that the MnB2 and MnB6 clusters are more stable than their neighbors. The magnetic moment of the MnB5 is the biggest among all of the MnB. clusters. The total magnetic moment of MnB. （n=5 and 7） clusters is mainly provided by the Mn atom. Except for n=3 and 5, the magnetic moment of clusters not only attributes to Mn but also B atom. Mulliken population analysis result showed that the magnetic moment of MnBn clusters mainly comes from the localized d electron, due to its asymmetric densities of d orbital states.

关 键 词：MnBn团簇 密度泛函理论 结构与稳定性 磁性 

分 类 号：O641[理学—物理化学] O482.5[理学—化学]