title: Coexisting Honeycomb and Kagome Characteristics in the Electronic Band Structure of Molecular Graphene.
abstract: We uncover the electronic structure of molecular graphene produced by adsorbed CO molecules on a copper (111) surface by means of first-principles calculations. Our results show that the band structure is fundamentally different from that of conventional graphene, and the unique features of the electronic states arise from coexisting honeycomb and Kagome symmetries. Furthermore, the Dirac cone does not appear at the K-point but at the Γ-point in the reciprocal space and is accompanied by a third, almost flat band. Calculations of the surface structure with Kekulé distortion show a gap opening at the Dirac point in agreement with experiments. Simple tight-binding models are used to support the first-principles results and to explain the physical characteristics behind the electronic band structures.
authors.affiliation: Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland.
authors.forename: Sami
authors.initials: S
authors.lastname: Paavilainen
authors.affiliation: Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland.|COMP Centre of Excellence, Department of Applied Physics, Aalto University , FI-00076 Aalto, Finland.
authors.forename: Matti
authors.initials: M
authors.lastname: Ropo
authors.affiliation: Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland.
authors.forename: Jouko
authors.initials: J
authors.lastname: Nieminen
authors.affiliation: Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland.|COMP Centre of Excellence, Department of Applied Physics, Aalto University , FI-00076 Aalto, Finland.
authors.forename: Jaakko
authors.initials: J
authors.lastname: Akola
authors.affiliation: Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland.
authors.forename: Esa
authors.initials: E
authors.lastname: Räsänen
keywords: Kagome; Kekulé; Molecular graphene; density functional theory; tight binding