The notion of strong electronic correlations arose in the context of d-metal oxides such as NiO but can be exemplified on systems as simple as the H2 molecule. Here we shed light on correlation effects on B62− clusters as found in MB6 hexaborides and show that the B 2p valence electrons are fairly correlated. B6-octahedron excitation energies computed for CaB6 and YbB6 agree with peak positions found by resonant inelastic x-ray scattering, providing a compelling picture for the latter. Our findings characterize these materials as very peculiar p-electron correlated systems and call for more involved many-body investigations within the whole hexaboride family, both alkaline- and rare-earth compounds, not only for N- but also (N±1)-states defining e. g. band gaps.
@article{arxiv.2211.05571,
title = {Quantum chemical insights into hexaboride electronic structures: correlations within the boron $p$-orbital subsystem},
author = {Thorben Petersen and Ulrich K. Rößler and Liviu Hozoi},
journal= {arXiv preprint arXiv:2211.05571},
year = {2022}
}