Optical properties of correlated materials -- Generalized Peierls approach and its application to VO2

TL;DR

This paper introduces a generalized Peierls approach for calculating optical properties of correlated materials, specifically applied to VO2, incorporating many-body effects and high-energy orbital transitions, with results aligning well with experiments.

Contribution

It extends the Peierls substitution to multi-atomic unit cells and develops an upfolding scheme for high-energy orbital transitions in optical calculations.

Findings

Accurate optical conductivity calculations for VO2 in metallic and insulating phases.

Good agreement between theoretical results and experimental optical spectra.

Enhanced methodology for realistic many-body optical property computations.

Abstract

The aim of the present paper is to present a versatile scheme for the computation of optical properties of solids, with particular emphasis on realistic many-body calculations for correlated materials. Geared at the use with localized basis sets, we extend the commonly known lattice "Peierls substitution" approach to the case of multi-atomic unit cells. We show in how far this generalization can be deployed as an approximation to the full Fermi velocity matrix elements that enter the continuum description of the response of a solid to incident light. We further devise an upfolding scheme to incorporate optical transitions, that involve high energy orbitals that had been downfolded in the underlying many-body calculation of the electronic structure. As an application of the scheme, we present results on a material of longstanding interest, vanadium dioxide, VO2. Using dynamical mean-field data of both, the metallic and the insulating phase, we calculate the corresponding optical conductivities, elucidate optical transitions and find good agreement with experimental results.