Strongly correlated electrons: Estimates of model parameters

TL;DR

This paper discusses methods to estimate renormalized parameters in model Hamiltonians for strongly correlated electrons, applying the approach to 3d and 4f compounds, and comparing theoretical and experimental data for fullerides.

Contribution

It introduces a simplified model for 3d compounds with renormalized parameters and applies it to calculate effective Coulomb integrals, including a comparison with experimental data.

Findings

Effective Coulomb integrals for 3d and 4f compounds calculated.

Comparison of theoretical and experimental data for fullerides.

Discussion of effects omitted in the simplified model.

Abstract

The determination of renormalized parameters in model Hamiltonians is discussed. A simple model of a 3d compound is studied, and it is shown how higher states can be projected out, resulting in a simpler model with renormalized parameters. This is applied to the calculation of effective Coulomb integrals for 3d and 4f compounds. Effects left out in this approach are discussed. We then focus on fullerides and compare theoretical and experimental data for the Coulomb interaction and the electron-phonon strength.