Fully {\it ab-initio} electronic structure of Ca$_{2}$RuO$_{4}$

TL;DR

This paper demonstrates that the GW+EDMFT method can reliably predict the electronic structure of the strongly correlated material Ca$_2$RuO$_4$, capturing its metal-insulator transition without user parameters.

Contribution

The study applies the parameter-free GW+EDMFT approach to Ca$_2$RuO$_4$, showing its effectiveness in accurately describing strongly correlated materials.

Findings

GW+EDMFT accurately predicts electronic properties of Ca$_2$RuO$_4$.

Nonlocal polarization and self-energy are crucial for correct interaction bandwidth balance.

The method captures the temperature-driven metal-insulator transition successfully.

Abstract

The reliable {\it ab-initio} description of strongly correlated materials is a long-sought capability in condensed matter physics. The $GW$+EDMFT method is a promising scheme, which provides a self-consistent description of correlations and screening, and does not require user-provided parameters. In order to test the reliability of this approach we apply it to the experimentally well characterized perovskite compound Ca$_2$RuO$_4$, in which a temperature-dependent structural deformation drives a paramagnetic metal-insulator transition. Our results demonstrate that the nonlocal polarization and self-energy components introduced by $GW$ are essential for setting the correct balance between interactions and bandwidths, and that the $GW$+EDMFT scheme produces remarkably accurate predictions of the electronic properties of this strongly correlated material.