Origin of Dirac Cones in SiC Silagraphene: A Combined
Density Functional and Tight-Binding Study
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Abstract
The formation of Dirac cones in electronic
band structures via
isomorphous transformation is demonstrated in 2D planar SiC sheets.
Our combined density functional and tight-binding calculations show
that 2D SiC featuring C–C and Si–Si atom pairs possesses
Dirac cones (DCs), whereas an alternative arrangement of C and Si
leads to a finite band gap. The origin of Dirac points is attributed
to bare interactions between Si–Si bonding states (valence
bands, VBs) and C–C antibonding states (conduction bands, CBs),
while the VB–CB coupling opens up band gaps elsewhere. A mechanism
of atom pair coupling is proposed, and the conditions required for
DC formation are discussed, enabling one to design a class of 2D binary
Dirac fermion systems on the basis of DF calculations solely for pure
and alternative binary structures