Structures and magnetic properties of SinNi (n = 1-17) clusters

The structure, electronic and magnetic properties of SinNi clusters up to n = 17 are systematically investigated using the density-functional theory (DFT) within the generalized gradient approximation (GGA). In the ground configurations of SinNi clusters, the equilibrium site of Ni atom gradually moves from convex, to a surface, and to a concave site as the number of Si atoms varying from 1 to 17. Starting from n = 8, the Ni atom completely falls into the center of the Si outer frame, forming Ni-encapsulated Si cages. Maximum peaks of second-order energy difference are found at n = 5, 7, 10, 12 and 14, indicating that these clusters possess relatively higher stability. Especially, Si10Ni cluster is more stable. The electronic structures and magnetic properties of SinNi clusters are discussed. The strong hybridization between Ni 4s, 3d, 4p and Si 3s, 3p states leads to the decrease of the gaps between highest-occupied and lowest-unoccupied molecular orbitals of SinNi clusters compared with corresponding those of Sin clusters and may be one of important factors which result in SinNi clusters magnetic moment quenched except for Si2Ni cluster.