Orbital-selective behavior in cubanite CuFe2S3

Using ab initio band structure calculations we show that mineral cubanite, ${\mathrm{CuFe}}₂{\mathrm{S}}₃$, demonstrates an orbital-selective behavior with some of the electrons occupying molecular orbitals of ${x}²\ensuremath{-}{y}²$ symmetry and others localized at atomic orbitals. This is a rare situation for $3d$ transition metal compounds that explains the experimentally observed absence of charge disproportionation, anomalous M\"ossbauer data, and ferromagnetic ordering in between nearest-neighbor Fe ions.