First-principles treatment of Mott insulators: linearized QSGW+DMFT approach

TL;DR

This paper introduces a novel first-principles method combining quasiparticle self-consistent GW and dynamical mean-field theory to accurately study Mott insulators and other strongly correlated quantum materials.

Contribution

It develops a new computational approach that enables first-principles analysis of Mott insulators in various magnetic phases, using localized orbitals and self-consistency on the Matsubara axis.

Findings

Accurately reproduces spectral properties of La2CuO4 and NiO.

Predicts magnetic moments consistent with experimental data.

Enables study of correlated insulators in paramagnetic and antiferromagnetic phases.

Abstract

The theoretical understanding of emergent phenomena in quantum materials is one of the greatest challenges in condensed matter physics. In contrast to simple materials such as noble metals and semiconductors, macroscopic properties of quantum materials cannot be predicted by the properties of individual electrons. One of the examples of scientific importance is strongly correlated electron system. Neither localized nor itinerant behaviors of electrons in partially filled 3d, 4f, and 5f orbitals give rise to rich physics such as Mott insulators, high-temperature superconductors, and superior thermoelectricity, but hinder quantitative understanding of low-lying excitation spectrum. Here we present a new first-principles approach to strongly correlated solids. It is Q4 based on a combination of the quasiparticle self-consistent GW approximation and the dynamical mean-field theory. The sole input in this method is the projector to the set of correlated orbitals for which all local Feynman graphs are being evaluated. For that purpose, we choose very localized quasiatomic orbitals spanning large energy window, which contains most strongly hybridized bands, as well as upper and lower Hubbard bands. The self-consistency is carried out on the Matsubara axis. This method enables the first-principles study of Mott insulators in both their paramagnetic and antiferromagnetic phases. We illustrate the method on the archetypical charge transfer correlated insulators La2CuO4 and NiO, and obtain spectral properties and magnetic moments in good agreement with experiments.