Probing the structures and electronic properties of dual-phosphorus-doped gold cluster anions ([formula omitted], n = 1–8): A density functional theory investigation

Abstract

The geometries of gold clusters doped with two phosphorus atoms, AunP2- (n=1–8), were investigated using density functional theory (DFT) methods. Various two-dimensional (2D) and three-dimensional (3D) structures of the doped clusters were studied. The results indicate that the structures of dual-phosphorus-doped gold clusters exhibit large differences from those of pure gold clusters with small cluster sizes. In our study, as for Au6P2-, two cis–trans isomers were found. The global minimum of Au8P2- presents a similar configuration to that of Au20-, a pyramid-shaped unit, and the potential novel optical and catalytic properties of this structure warrant further attention. The higher stability of AunP2- clusters relative to Aun+2- (n=1–8) clusters was verified based on various energy parameters, and the results indicate that the phosphorus atom can improve the stabilities of the gold clusters. We then explored the evolutionary path of AunP2- (n=1–8) clusters. We found that AunP2- clusters exhibit the 2D–3D structural transition at n=6, which is much clearer and faster than that of pure gold clusters and single-phosphorus-doped clusters. The electronic properties of AunP2- (n=1–8) were then investigated. The photoelectron spectra provide additional fundamental information on the structures and molecular orbitals shed light on the evolution of AunP2- (n=1–8). Natural bond orbital (NBO) described the charge distribution in stabilizing structures and revealed the strong relativistic effects of the gold atoms.