A DFT-Based Investigation of the properties of gold nanoclusters up to Au20

Abstract

The structures and stabilities of gold clusters with up to 20 atoms have been studied by Density Functional Theory (DFT) and compared in two vacuum and COSMO environment here for the first time. The structure optimizations and frequency analysis are performed with the Generalized Gradient Approximation (GGA) BLYP (Becke, 1988; Lee et al., 1988) functional in Dmol3 combined with the all-electron relativistic core treatment and corresponding Double Numerical plus Polarization (DNP) basis set. The transition point from two-dimensional to three-dimensional geometry for gold clusters occurs at Au17 in both the vacuum and COSMO environment. The structural, energetic, and electronic properties of the small gold clusters strongly depend on sizes and structures, which are in good agreement with other theoretical and experimental calculations. It was also found that the effect of relativistic properties has a great influence on the properties of gold clusters. The even-odd oscillation (saw-tooth patterns) observed in the different properties of the clusters predicts the stability of the clusters and their electronic properties. The result shows that the clusters with even numbers of atoms were more stable than the neighboring clusters with odd numbers of atoms due to their closed-shell orbital structure. Also, the properties of gold nanoclusters in COSMO seem to be different from the vacuum environment.