Electronic structure and magnetism of clusters Nin(n=2-6)
Nin(n=2-6)原子簇的电子结构和磁性研究

The electronic structure and magnetism of clusters Nin(n=2-6) have been studied by spin-polarized MS-Xa method. The results show that the effect of the cluster symmetry on its atomic magnetic moment and electronic density of states is very notable. Ni6 cluster is an octahedron belonging to Oh point group. Its 3Eg orbital presents strong negative exchange coupling and has a trend of antiferromagnetic couplings. Ni5 cluster is of three-side pyramidal structure belonging to point group C3v. The magnetic moment direction of Ni atom lying on vertex of the pyramid is antiparallel to the moment direction of the Ni atoms lying on underside of the pyramid, which present the characteristic of ferrimagnetic couplings. Compared with metal nickel, the magnetic moments of some clusters are enhanced and some are weakened. The abnormal phenomenon of surface magnetism of ferromagnetic superfine particles can be well explained using this result.