Structural stability and electronic properties of small gold clusters induced by 3p electron atoms

Abstract

The geometries and electronic properties of gold clusters doped with atoms containing 3p valence electrons (MAun; M = Al, Si, P, S, Cl; n = 2−8) have been systematically investigated using density functional theory (DFT) at the PBE/LANL2DZ level. A number of low-energy isomers are identified for neutral MAun clusters. It is found that doping with different 3p impurity atoms can drastically influence the geometrical structures, relative stabilities, electronic properties, and growth-pattern behaviors of gold clusters, which is very different from the case of 3d transition-metal impurity doped Aun clusters. Partially filled 3p electron impurities can stabilize Au clusters. In particular, SiAu4 cluster with Td symmetry have been found to have highly stable geometries and electronic structures with binding energies of 2.43 eV per atom (0.96 eV higher than pristine Au5 clusters), large HOMO-LUMO gaps (2.17 eV), and vertical ionization potentials of 8.68 eV. Using scalar relativistic molecular dynamics at T = 300 K, we show that the Td symmetry structure of SiAu4 is stable. The frontier molecular orbitals (HOMO and LUMO) and the partial densities of states (PDOS) show that strong hybridization occurs between the atomic orbitals of Si and Au atoms, resulting in strong Si-Au bonding. In addition, the vertical ionization potential, the vertical electron affinity, and charge transfers of MAun clusters have also been analyzed. Our results are in good agreement with available experimental data.