Structures and magnetic properties of Si nNi ( n = 1–17) clusters

Abstract

The structure, electronic and magnetic properties of Si n Ni 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 Si n Ni 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, Si 10Ni cluster is more stable. The electronic structures and magnetic properties of Si n Ni 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 Si n Ni clusters compared with corresponding those of Si n clusters and may be one of important factors which result in Si n Ni clusters magnetic moment quenched except for Si 2 Ni cluster.