Fig. 4. (Color online) (a) Evolution of the band gap of Si2Bi2 as a function of bi-axial strain. a0 and a indicate respectively the pristine and strained in-plane lattice constants. (b) Electronic band structure along the A-Γ-A direction at (a − a0)/a0 = −1.497 %. (c) Energy differences between the Dirac point ED and Fermi level EF as a function of strain. (d) Electronic band structure along the A-Γ-A direction at (a − a0)/a0 = −1.296 %. For strain of (a − a0)/a0 > −1.296 %, Si2Bi2 becomes a trivial conductor.
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