Atomic structures and electronic properties of small Au–Ag binary clusters: Effects of size and composition

Genetic algorithm combined with first-principle calculations is used to globally search the potential energy surface of the most stable configurations of elementary Aum and Agn clusters, as well as AumAgn (5 ⩽ m + n ⩽ 12) binary clusters. The effects of size and composition (i.e., Au:Ag ratio) on the atomic structures, coordination numbers and electronic properties including the binding energies and formation energies of Au–Ag binary clusters are discussed. The critical Au:Ag ratios for the 2D–3D transition are obtained and it is found that Ag atoms sometimes play a more important role in determining the ground-state configuration of a Au–Ag bimetallic cluster. The electron density of states is further analyzed to explore the influence of Au and Ag atoms. Stronger s–d hybridization originated from relativistic effects of Au atom is observed in the planar structure with regard to the 3D structures.