Author(s)

Akira Suzuki¹, Masashi Tanabe¹, Shigeji Fujita²

¹Department of Physics, Faculty of Science, Tokyo University of Science, Tokyo, Japan.
²Department of Physics, University at Buffalo, State University of New York, Buffalo, NY, USA.

The Wigner-Seitz unit cell (rhombus) for a honeycomb lattice fails to establish a k-vector in the 2D space, which is required for the Bloch electron dynamics. Phonon motion cannot be discussed in the triangular coordinates, either. In this paper, we propose a rectangular 4-atom unit cell model, which allows us to discuss the electron and phonon (wave packets) motion in the k-space. The present paper discusses the band structure of graphene based on the rectangular 4-atom unit cell model to establish an appropriate k-vector for the Bloch electron dynamics. To obtain the band energy of a Bloch electron in graphene, we extend the tight-binding calculations for the Wigner-Seitz (2-atom unit cell) model of Reich et al. (Physical Review B, 66, Article ID: 035412 (2002)) to the rectangular 4-atom unit cell model. It is shown that the graphene band structure based on the rectangular 4-atom unit cell model reveals the same band structure of the graphene based on the Wigner-Seitz 2-atom unit cell model; the π-band energy holds a linear dispersion (ε−k ) relations near the Fermi energy (crossing points of the valence and the conduction bands) in the first Brillouin zone of the rectangular reciprocal lattice. We then confirm the suitability of the proposed rectangular (orthogonal) unit cell model for graphene in order to establish a 2D k-vector responsible for the Bloch electron (wave packet) dynamics in graphene.

Graphene, Rectangular 4-Atom Unit Cell Model, Primitive Orthogonal Basis Vector, Bloch Electron (Wave Packet) Dynamics, k-Vector, Dirac Points, Linear Dispersion Relation

Suzuki, A. , Tanabe, M. and Fujita, S. (2017) Electronic Band Structure of Graphene Based on the Rectangular 4-Atom Unit Cell. Journal of Modern Physics, 8, 607-621. doi: 10.4236/jmp.2017.84041.