Structural, vibrational, and quasiparticle properties of the Peierls semiconductor BaBiO(3): A hybrid functional and self-consistent GW plus vertex-corrections study

BaBiO3is characterized by a charge disproportionation with half of the Bi atoms possessing a valence 3+and half a valence 5+. Because of self-interaction errors, local- and semilocal-density functionals fail todescribe the charge disproportionation quantitatively, yielding a too small structural distortion and no band gap.Using hybrid functionals, we obtain a satisfactory description of the structural, electronic, optical, and vibra-tional properties of BaBiO3. The results obtained using GWGreen’s function G and screened Coulombpotential Wbased schemes on top of hybrid functionals, including fully self-consistent GW calculations withvertex corrections in the dielectric screening, qualitatively confirm the Heyd-Scuseria-Ernzerhof picture but asystematic overestimation of the band gap by about 0.4 eV is obser