Towards a First-Principles Determination of Effective Coulomb Interactions in Correlated Electron Materials: Role of Intershell Interactions

The determination of the effective Coulomb interactions to be used in low-energy Hamiltonians for materials with strong electronic correlations remains one of the bottlenecks for parameter-free electronic structure calculations. We propose and benchmark a scheme for determining the effective local Coulomb interactions for charge-transfer oxides and related compounds. Intershell interactions between electrons in the correlated shell and ligand orbitals are taken into account in an effective manner, leading to a reduction of the effective local interactions on the correlated shell. Our scheme resolves inconsistencies in the determination of effective interactions as obtained by standard methods for a wide range of materials, and allows for a conceptual understanding of the relation of cluster model and dynamical mean field-based electronic structure calculations.

Figure 1

$U(\omega )$ for $df\text{−}df$ and effective (SF) Hamiltonians for cerium. For $U^{ff}$ and $U^{dd}$ the monopole term $F^0$ is plotted and for $U^{df}$ we give an orbital average.

Figure 2

PES and IPES spectra for ${\mathrm{UO}}_2$ using interaction parameters obtained in the $f\text{−}f$, $f\text{−}fp$, and SF models compared to experimental spectra [111, 112, 113].