# Effective band-structure in the insulating phase versus strong dynamical correlations in metallic VO2

## TL;DR

This paper investigates the electronic structure of VO2's metallic and insulating phases, revealing that the insulator can be described by an effective band-structure despite strong correlations, characterizing it as a 'many-body Peierls' state.

## Contribution

The study introduces an analytical continuation scheme for cluster DMFT calculations, enabling the construction of an orbital-dependent static potential that captures the many-body spectrum of VO2.

## Key findings

- Insulating VO2 exhibits an effective band-structure.
- Metallic VO2 shows dynamical correlation effects preventing quasiparticle description.
- The insulator is characterized as a 'many-body Peierls' state.

## Abstract

Using a general analytical continuation scheme for cluster dynamical mean field calculations, we analyze real-frequency self-energies, momentum-resolved spectral functions, and one-particle excitations of the metallic and insulating phases of VO2. While for the former dynamical correlations and lifetime effects prevent a description in terms of quasi-particles, the excitations of the latter allow for an effective band-structure. We construct an orbital-dependent, but static one-particle potential that reproduces the full many-body spectrum. Yet, the ground state is well beyond a static one-particle description. The emerging picture gives a non-trivial answer to the decade-old question of the nature of the insulator, which we characterize as a ``many-body Peierls'' state.