Insulator-Metal Transition in the Rutile-based VO2

TL;DR

This paper investigates the metal-insulator transition in VO2 using LDA+DMFT, revealing a new spectral weight transfer mechanism linked to V ion displacement, with results aligning well with experimental data.

Contribution

It introduces a novel understanding of the MIT in VO2 through spectral weight transfer and strong correlation effects within the LDA+DMFT framework.

Findings

Spectral weight transfer correlates with V ion displacement.

Good agreement with experimental orbital occupation and spectral functions.

Comparison with QMC-based approaches confirms robustness.

Abstract

The metal-insulator transition (MIT) in paramagnetic VO2 is studied within LDA+DMFT(IPT), which merges the local density approximation (LDA) with dynamical mean field theory (DMFT). With a fixed value of the Coulomb U=5.0eV, we show how the MIT is understood in a new picture: spectral weight transfer accompanying the increase in the displacement of V ion ($\perp c$) within the strong correlation scenario. Within this new scenario, we find good quantitative agreement with (i) switch of the orbital occupation of (xy,yz+zx,yz-zx), (ii) thermodynamics, and (iii) the one-electron spectral function in the metallic phase of VO2. We also compare our results for the total spectral density with other approaches which use QMC to solve the impurity problem of DMFT.