Fig. 5: The non-interacting band structure of the two-dimensional sp-model in the insulating (bond disproportionated) state and in hole language.

Panels a and b are fat band plots showing the degree of Ls and Ld weight in each of the bands, respectively. Panel c is the total DOS and its orbital components. The completely occupied band below the Fermi level is the Bi 6s/Ls bonding band orbitals. The first band above the Fermi level is composed of Lx,y and Ld orbitals.