Structural and Electronic Properties of Stable AunIr2 (n = 1 – 7) Clusters: Comparison with Pure Gold Clusters

Abstract

The geometrical structures, relative stabilities, electronic and magnetic properties of AunIr2 (n = 1 - 7) clusters have been systematically investigated by using meta-generalized gradient approximation (meta-GGA) Tao-Perdew-Staroverov-Scuseria (TPSS) functional in comparison with pure gold clusters. The optimized geometries show that the two doping iridium atoms can affect the structure of the host cluster. Compared with the pure Aun+2 clusters, the lowest energy AunIr2 (n=1 - 7) clusters favour higher spin multiplicity except for Au7Ir2. Furthermore, the calculated binding energies, fragmentation energies, second-order difference energies, and the highest occupied-lowest unoccupied energy gaps indicate that the stability of AunIr2 is enhanced. Natural population analysis reveals that the charges transfer from the Aun frames to the iridium atoms for Au3;4;6;7Ir2 clusters. In addition, charges and magnetic moments of 6s, 5d, and 6p states for the iridium atoms in AunIr2 (n = 1 - 7) clusters are also analyzed and compared.