A selection of theoretical routes used for the simulation of the relevant core edges (Fe L₂₃ in (a), O K in (c)), compared to experimental spectra on a hematite α-Fe₂O₃ thin foil. They are respectively based on an atomic multiplet approach for Fe³⁺ ions and octahedral O_h crystal field of 2 eV (a) or on a band structure one in the DFT (Local Spin-Density Approximation (LSDA)) model (c). In (b), simplified description of the relevant MOs as an hybridization of the O-2p and Fe-3d atomic orbitals [66]. (figure with courtesy of Alexandre Gloter).