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The equilibrium geometric structures, relative stabilities, and electronic properties of AunC- and Aun+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 Aun-1C- clusters is a dominant growth pattern for AunC- clusters. In contrast to Aun+1- clusters, AunC- 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 Aun- host decreases with the increase of cluster size. The HOMO-LUMO gap curves show that the interaction of the C atom with Aun- 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 AunC- clusters transfer from the Aun- 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. [ABSTRACT FROM AUTHOR]

The equilibrium geometric structures, relative stabilities, electronic stabilities, and electronic and magnetic properties of the Au n C and Au n +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 Au n −1 C cluster is the dominant growth pattern for the Au n C clusters. In contrast to the pure gold clusters, the Au n C 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 Au 6,8 C clusters who have 2D structures. The analysis of the relative and electronic stabilities reveals that the Au 4 C and Au 6 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 Au n C clusters transfer from the Au n 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 Au n C clusters. As for the magnetic properties of the Au n C clusters, the total magnetic moments are 1 μ B for n = odd clusters, with the total magnetic moments mainly locating on the C atoms for Au 1,3,9 C and on the Au n host for Au 5,7 C clusters. However, the total magnetic moments of the Au n C 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. [ABSTRACT FROM AUTHOR]

By means of density functional theory calculations, we successfully predict two stable 2D triangular borophenes, namely B3H and B6O. Our results indicate that B3H is a Dirac material and its cone point is located at the K point of the Brillouin zone (BZ). B6O is identified as having a node-line ring and Dirac cones together. Its node-line ring formed by the intersection of the extended energy band from the two Dirac cones located on K point. This modified 2D borophene has great thermal and dynamic stability due to the electron transfer from the triangular boron lattice to the O atoms. The electronic structure of B6O nanofilm demonstrates novel properties such as two Dirac cones, more than 1.3 eV linear dispersion bands at some points of the BZ, as well as excellent transport properties for the extremely high mobility brought by the combination of the node-line semimetal and Dirac cones. Our study may motivate potential applications of 2D materials in nanoelectronics. [ABSTRACT FROM AUTHOR]