Towards a first-principles determination of effective Coulomb interactions in correlated electron materials: Role of intershell interactions

TL;DR

This paper introduces a first-principles scheme to accurately determine effective Coulomb interactions in correlated materials, accounting for intershell effects to improve electronic structure calculations.

Contribution

The authors develop and benchmark a novel method that includes intershell interactions, reducing effective local Coulomb interactions and resolving inconsistencies in standard approaches.

Findings

Intershell interactions significantly reduce effective Coulomb interactions.

The scheme improves consistency across different materials.

It bridges cluster model and dynamical mean field approaches.

Abstract

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.