Geometrical Structures And Electronic Properties Of Doping Gold Clusters Studied By The First-principles Calculations

In the past decades, gold clusters (AuN) have attracted much attention due to their tremendous potential applications in catalysis, biology, and nanoscale devices, making them become a hot research topic in the nano-sized material science. Considering that doping can offer chemical versatility for tuning the structural, electronic, and catalytic properties of AuN, we have investigated the structural and electronic properties of doping gold clusters by the first-principles calculations in this thesis. The thesis is divided into the following four chapters.In Chapter1, we have briefly introduced the previous theoretical and experimental works on the pure AuN and doping gold clusters.In Chapter2, we have presented the background of the first-principles calculations and shown how the Kohn-Sham equation in the density functional theory is derived and how to solve it practically. Also, we have introduced the relativistic effect of noble metals. Finally, we have introduced the software (DMOL3) adopted in our calculations.In Chapter3, the structural and electronic properties of MnAu20-n-(M=Cu and Na; n=1and2) have been investigated by the relativistic density-functional calculations. It is found that the most stable configurations of CuAu19-and Cu2Au18-are the face-centered and two-face-centered doped structures based upon the tetrahedral structure of Au20-. In contrast, the ground states of Na-doped gold clusters (NaAu19- and Na2Au18-) exhibit flat-cage configurations. The PES of these ground states are depicted that may be helpful to identify their configurations in the future experiments. The face-centered and two-face-centered doped tetrahedral structures of CuAu19-and Cu2Au18-have a large energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), indicating that they are chemically stable.In Chapter4, the geometrical structures and electronic properties of MnAu24-n-(M=Ag and Cu; n=1and2) have been studied preliminary using the density functional theory calculations. It is found that the tubular configuration of Au24-cannot be kept as the ground states due to the addition of Cu or Ag. The most stable configurations of AgAu23-and CuAu23-are the double-layered flat-cage structures, but Ag2Au22-and Cu2Au22-exhibit endohedral structures, indicating that the number of doped atoms affects the structures of the doped clusters.