The geometric structures, stabilities, and electronic properties of bimetallic Rb2Aun (n = 1–10) clusters: A density functional theory study

Abstract

The geometric structures, relative stabilities, growth patterns, and electronic properties of pure and Rb2-substituted Aun+2 (n=1–10) clusters are investigated by using the density functional theory within generalized gradient approximation in conjunction with a valence electron basis set. The stable geometries with different spin multiplicities are determined. The results show that doping gold clusters with two Rb atoms dramatically affects the ground-state geometries of the pure gold clusters, the doped Rb atoms prefer locating on the surface and mirror symmetry positions, and the Au-capped Rb2Aun–1 clusters are the dominant growth pattern. The ground-state structures of Rb2Aun (n⩾3) clusters tend to be considered as three dimensional configurations with a two dimensional (or only slightly tilted) gold subunits motif. The energetic and electronic properties of the Rb2Aun and Aun+2 (n=1–10) clusters are strongly dependent on sizes and structures. The average atomic binding energies show that the doped Rb atoms enhance the stabilities of host clusters for the larger clusters (n>5). Dramatic odd–even alternative behaviors are found in the fragmentation energies, the second-finite difference of energies, the HOMO–LUMO gaps, VIPs, and chemical hardness for both Rb2Aun and Aun+2 (n=1–10) clusters. In addition, it is found that Rb2Au6 isomer is the most stable of the Rb2Aun (n=1–10) clusters.