A density functional theory study on structures, stabilities, and electronic and magnetic properties of AunC (n = 1–9) clusters

The equilibrium geometric structures, relative stabilities, electronic stabilities, and electronic and magnetic properties of the AunC and Aun+1 (n=1–9) clusters are systematically investigated using density functional theory (DFT) with hyper-generalized gradient approximation (GGA). The optimized geometries show that one Au atom added to the Aun−1C cluster is the dominant growth pattern for the AunC clusters. In contrast to the pure gold clusters, the AunC clusters are most stable in a quasi-planar or three-dimensional (3D) structure because the C dopant induces the local non-planarity, with exceptions of the Au6,8C clusters who have 2D structures. The analysis of the relative and electronic stabilities reveals that the Au4C and Au6 clusters are the most stable in the series of studied clusters, respectively. In addition, a natural bond orbital (NBO) analysis shows that the charges in the AunC clusters transfer from the Aun host to the C atom. Moreover, the Au and C atoms interact with each other mostly via covalent bond rather than ionic bond, which can be confirmed through the average ionic character of the Au–C bond. Meanwhile, the charges mainly transfer between 2s and 2p orbitals within the C atom, and among 5d, 6s, and 6p orbitals within the Au atom for the AunC clusters. As for the magnetic properties of the AunC clusters, the total magnetic moments are 1μB for n=odd clusters, with the total magnetic moments mainly locating on the C atoms for Au1,3,9C and on the Aun host for Au5,7C clusters. However, the total magnetic moments of the AunC clusters are zero for n=even clusters. Simultaneously, the magnetic moments mainly locate on the 2p orbital within the C atom and on the 5d, 6s orbitals within the Au atom.