First-principles study of dielectric properties of ferroelectric perovskite oxides with on-site and inter-site Hubbard interactions

TL;DR

This study employs self-consistent extended Hubbard functionals to accurately predict the electronic and ferroelectric properties of perovskite oxides, achieving results comparable to hybrid functionals but at lower computational cost.

Contribution

The paper introduces a self-consistent extended Hubbard functional approach that improves the accuracy of electronic property calculations for ferroelectric perovskites, aligning well with experimental data and hybrid functional results.

Findings

Extended Hubbard functionals increase band gap accuracy.

Inter-site Coulomb interactions restore polar instability.

Method reduces computational cost compared to hybrid functionals.

Abstract

We study the atomic and electronic structures of ferroelectric perovskite oxides, BaTiO$_3$, LiNbO$_3$, and PbTiO$_3$ using ab initio extended Hubbard functionals in which the on-site and inter-site Hubbard interactions are determined self-consistently, adapted from the pseudohybrid density functional proposed by Agapito-Curtarolo-Buongiorno Nardelli. Band structures, ferroelectric distortions, polarization, Born effective charges, and switching barriers are calculated with extended Hubbard functionals, that are compared with those using local density approximation (LDA), generalized gradient approximation (GGA), and Hybrid (HSE06) functionals. The properties of all three compounds calculated by extended Hubbard functionals are in good agreement with experimental data. We find a substantial increase in band gaps due to the inter-site Coulomb interactions, which show better agreement with $GW$ results compared to those from LDA and GGA functionals. The crucial role of the inter-site Coulomb interactions in restoring the suppressed polar instability, which is computed when only the on-site Hubbard interactions are considered, is also highlighted. Overall, we find that the properties calculated using our extended Hubbard functionals exhibit trends similar to those obtained with the HSE06 functional, while reducing computational costs by over an order of magnitude. Thus, we propose that the current method is well-suited for high-throughput calculations for perovskite oxides, offering significantly improved accuracy in computing band gap and other related physical properties such as the shift current photovoltaic effect and band alignments in ferroelectric heterostructures.