Segregation Effect and Its Influence on the Stability and Electronic Properties of Icosahedral CuxAg13−x (x = 0–13) Clusters

Abstract

The icosahedral CuxAg13−x (x = 0–13) clusters are calculated using an effective sampling method and first-principle calculations based on density functional theory. And the segregation effect and its influence on the stability and electronic properties of the clusters are investigated. The calculation results show that the stability of CuxAg13−x greatly depends on the occupation position of Cu atoms and their segregation degree. The HOMO–LUMO gap of CuxAg13−x is closely related to the segregation degree of Cu atoms as well as the composition ratio between Cu and Ag. And an optimized Cu7Ag6 cluster, in which Cu atoms have the largest segregation degree, is found to be the largest HOMO–LUMO gap. By analyzing the local density of states, bond strength, bond length and bond ratio, we reveal the origin of the segregation effect and its influence on the HOMO–LUMO gap of CuxAg13−x. The results presented in this work are helpful to design the bimetallic clusters with stable structures and desired electronic properties.