Fig. 7. LCAO representations of (A) the conduction band (CB) at L and Γ and (B) the valence band (VB) at X and Γ for Cs₂AgBiBr₆, obtained using the LCAO theory illustrated in Fig. 5. Net nonbonding interactions between the halide SALCs and the metal s orbitals explain the missing Ag 5s⁰ (orange arrow) and Bi 6s² (red arrow) orbital contributions at Γ at the CB and VB, respectively. Colored and empty lobes represent positive and negative phases, respectively. (C) Band structure of the double perovskite Cs₂AgBiBr₆ computed using DFT, showing an indirect gap from X to L. The band structure is shown in duplicate and the orbital contributions of the B-site atoms (Ag and Bi) are given in color with the dot size proportional to the size of the orbital contribution. Bromide contributions are present but not shown. Note that Ag 5s character is absent at the Γ point in the CB and that Bi 6s character is absent at the Γ point in the VB (denoted by orange and red arrows, respectively), in agreement with the LCAO analysis.