Insights and challenges of applying the $GW$ method to transition metal oxides

TL;DR

This paper investigates the application of the $GW$ method to transition metal oxides, analyzing the impact of common approximations on band gap calculations and identifying suitable approaches for TMOs.

Contribution

It provides a detailed comparison of $GW$ approximations for TMOs, clarifying their effects on band gap predictions and guiding future computational choices.

Findings

Different plasmon-pole models yield varying band gap results.

Some approximations align better with experimental data for TMOs.

The study highlights the limitations of traditional $GW$ methods for TMOs.

Abstract

The ab initio $GW$ method is considered as the most accurate approach for calculating the band gaps of semiconductors and insulators. Yet its application to transition metal oxides (TMOs) has been hindered by the failure of traditional approximations developed for conventional semiconductors. In this work, we examine the effects of these approximations on the values of band gaps for ZnO, Cu$_2$O, and TiO$_2$. In particular, we explore the origin of the differences between the two widely used plasmon-pole models. Based on the comparison of our results with the experimental data and previously published calculations, we discuss which approximations are suitable for TMOs and why.