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Paper   IPM / Nano-Sciences / 11682
School of Nano Science
  Title:   Energy gap opening in submonolayer lithium on graphene: Local density functional and tight-binding calculations
1.  Mani Farjam
2.  Hashem Rafii Tabar
  Status:   Published
  Journal: Phys. Rev. B
  No.:  4
  Vol.:  79
  Year:  2009
  Pages:   7
  Publisher(s):   The American Physical Society
  Supported by:  IPM
The adsorption of an alkali-metal submonolayer on graphene occupying every third hexagon of the honeycomb lattice in a commensurate (√3×√3)R30° arrangement induces an energy gap in the spectrum of graphene. To exemplify this type of band gap, we present ab initio density functional theory calculations of the electronic band structure of C6Li. An examination of the lattice geometry of the compound system shows the possibility that the nearest-neighbor hopping amplitudes have alternating values constructed in a Kekulé-type structure. The band structure of the textured tight-binding model is calculated and shown to reproduce the expected band gap as well as other characteristic degeneracy removals in the spectrum of graphene induced by lithium adsorption. More generally we also deduce the possibility of energy gap opening in periodic metal on graphene compounds CxM if x is a multiple of 3.

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