Frequency-dependent local interactions and low-energy effective models from electronic structure calculations

TL;DR

This paper introduces a first-principles method to derive frequency-dependent local interactions for strongly correlated materials, improving low-energy models by incorporating dynamic Coulomb screening effects.

Contribution

It presents a systematic scheme to compute frequency-dependent Coulomb interactions from GW calculations and integrate them into effective low-energy models.

Findings

Frequency-dependent U significantly affects spectral functions.

Energy dependence of U can be incorporated into simplified models.

Method enables more accurate modeling of strongly correlated materials.

Abstract

We propose a systematic procedure for constructing effective models of strongly correlated materials. The parameters, in particular the on-site screened Coulomb interaction U, are calculated from first principles, using the GW approximation. We derive an expression for the frequency-dependent U and show that its high frequency part has significant influence on the spectral functions. We propose a scheme for taking into account the energy dependence of U, so that a model with an energy-independent local interaction can still be used for low-energy properties.