Quantum chemical insights into hexaboride electronic structures: correlations within the boron p-orbital subsystem

Abstract The notion of strong electronic correlations arose in the context d -metal oxides such as NiO but can be exemplified on systems simple H 2 molecule. Here we shed light correlation effects B 6 2− clusters found M hexaborides and show that p valence electrons are fairly correlated. -octahedron excitation energies computed for CaB YbB agree with peak positions by resonant inelastic x-ray scattering, providing a compelling picture latter. Our findings characterize these materials very peculiar -electron correlated call more involved many-body investigations within whole hexaboride family, both alkaline- rare-earth compounds, not only N - also ( ± 1)-states defining e. g. band gaps.