Structures, energetics and magnetic properties of (NiSn)n clusters with n=1-6

We report the results of calculations which were performed to investigate equilibrium structures, electronic and magnetic properties of stoichiometric (NiSn)(n) clusters with n = 1-6 within the framework of density functional theory. The calculated results show that the structural arrangement of (NiSn)(n) clusters is dominated by the Ni-Sn and Ni-Ni interactions. We find that these binary clusters show significant variation in the geometries as compared to that of the host nickel clusters. The preference for tetrahedron unit of Ni3Sn is seen in the lowest-energy configuration of these clusters. The multi-centre bonding between Ni atoms play an important role in stabilizing the stoichiometric Ni-Sn clusters. Doping of Sn atoms enhances the binding energy and reduces the ionization potential of nickel clusters. These binary clusters prefer the lowest spin state. For (NiSn)(6) the magnetic moment is 0 mu B. The complete quenching of the cluster magnetic moment appears to be due to the anti ferromagnetic alignment of atomic spins as revealed by the spin density plots.