Optical and excitonic properties of transition metal oxide perovskites by the Bethe-Salpeter equation

TL;DR

This study systematically investigates excitonic effects on the optical properties of transition metal oxide perovskites using the Bethe-Salpeter equation, covering a diverse set of compounds with varying band gaps and properties.

Contribution

It provides a comprehensive analysis of excitonic effects in perovskites using BSE and introduces a benchmarked model-BSE approach for accurate exciton binding energy calculations.

Findings

Good agreement between theoretical and experimental optical spectra.

Excitonic effects significantly influence optical properties across all studied perovskites.

Model-BSE provides reliable exciton binding energies with reduced computational cost.

Abstract

We present a systematic investigation of the role and importance of excitonic effects on the optical properties of transitions metal oxide perovskites. A representative set of fourteen compounds has been selected, including 3$d$ (SrTiO$_3$, LaScO$_3$, LaTiO$_3$, LaVO$_3$, LaCrO$_3$, LaMnO$_3$, LaFeO$_3$ and SrMnO$_3$), 4$d$ (SrZrO$_3$, SrTcO$_3$ and Ca$_2$RuO$_4$) and 5$d$ (SrHfO$_3$, KTaO$_3$ and NaOsO$_3$) perovskites, covering a band gap ranging from 0.1 eV to 6.1 eV and exhibiting different electronic, structural and magnetic properties. Optical conductivities and optical transitions including electron-hole interactions are calculated through the solution of the Bethe-Salpeter equation (BSE) with quasi-particle energies evaluated by single-shot $G_0W_0$ approximation. The exciton binding energies are computed by means of a model-BSE (mBSE), carefully benchmarked against the full BSE method, in order to obtain well-converged results in terms of k-point sampling. The predicted results are compared with available measured data, with an overall satisfactory agreement between theory and experiment.