  The recent discovery nickel oxides superconductors have highlighted the
importance of first-principles simulations for understanding the formation of
the bound electrons at the core of superconductivity. Nevertheless,
superconductivity in oxides is often ascribed to strong electronic correlation
effects that Density Functional Theory (DFT) cannot properly take into account,
thereby disqualifying this technique. Being isostructural to nickel oxides,
Sr1-xKxBiO3 superconductors form an ideal testbed for unveiling (i) the lowest
theory level needed to model complex superconductors and (ii) the underlying
pairing mechanism yielding superconductivity. Here I show that parameter-free
DFT simulations capture all the experimental features and related quantities of
Sr1-xKxBiO3 superconductors, encompassing the prediction of an insulating to
metal phase transition upon increasing the K doping content and of an
electron-phonon coupling constant of 1.22 in sharp agreement with the
experimental value of 1.3 +/- 0.2. Proximity of a disproportionated phase is
further demonstrated to be a prerequisite for superconductivity in bismuthates.
This work highlights that appropriately executed DFT is a sufficient platform
for studying superconductivity in complex oxides.
