Growth behavior and electronic properties of NiAln (n = 1–14) clusters

A systematic theoretical study on the growth behavior and electronic properties of NiAln (n = 1–14) clusters has been performed in the framework of density-functional theory (DFT). In the ground-state structures of NiAln clusters, the equilibrium site of Ni atom gradually moves from convex, surface, to interior site as the number of Al atom varying from 2 to 14. Starting from n = 12, Ni atom completely falls into the center of the Al outer frame, forming Ni-encapsulated Al cage. The changes of Ni atom sites as the number of Al atoms increase can maximize the number of Ni–Al bonds. The Ni atom doping enhances the stabilities of aluminum clusters. The NiAl3, NiAl7 and NiAl13 clusters possess relatively higher stability than their neighboring clusters. The strong on-site sp-d hybridization on Ni atom and on Al atoms should be responsible for the behavior of the HOMO–LUMO gap with the cluster size in NiAln clusters.