Structure, stability, and electronic property of carbon-doped gold clusters Au_nC⁻ (n = 1–10): A density functional theory study

The equilibrium geometric structures, relative stabilities, and electronic properties of Au_nC⁻ and Au_n+1⁻ (n = 1–10) clusters are systematically investigated using density functional theory with hyper-generalized gradient approximation. The optimized geometries show that one Au atom capped on Au_n−1C⁻ clusters is a dominant growth pattern for Au_nC⁻ clusters. In contrast to Au_n+1⁻ clusters, Au_nC⁻ clusters are most stable in a quasi-planar or three-dimensional structure because C doping induces the local non-planarity while the rest of the structure continues to grow in a planar mode, resulting in an overall non-2D configuration. The relative stability calculations show that the impurity C atom can significantly enhance the thermodynamic stability of pure gold clusters. Moreover, the effect of C atom on the Au_n⁻ host decreases with the increase of cluster size. The HOMO-LUMO gap curves show that the interaction of the C atom with Au_n⁻ clusters improves the chemical stability of pure gold clusters, except for Au₃⁻ and Au₄⁻ clusters. In addition, a natural population analysis shows that the charges in corresponding Au_nC⁻ clusters transfer from the Au_n⁻ host to the C atom. Meanwhile, a natural electronic configuration analysis also shows that the charges mainly transfer between the 2s and 2p orbitals within the C atom.