Combining nonresonant inelastic x-ray scattering experiments with state-of-the-art ab initio many-body calculations, we investigate the electronic screening mechanisms in strongly correlated CuO in a large range of energy and momentum transfers. The excellent agreement between theory and experiment, including the low-energy charge excitations, allows us to use the calculated dynamical screening as a safe building block for many-body perturbation theory and to elucidate the crucial role played by d-d excitations in renormalizing the band gap of CuO. In this way we can dissect the contributions of different excitations to the electronic self-energy which is illuminating concerning both the general theory and this prototypical material.
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Rödl, C., Ruotsalainen, K. O., Sottile, F., Honkanen, A-P.
, Ablett, J. M., Rueff, J-P., ... Huotari, S.
(2017). Low-energy electronic excitations and band-gap renormalization in CuO
. Physical Review B
(19), . https://doi.org/10.1103/PhysRevB.95.195142