High- and low-energy many-body effects of graphene in a unified approach

TL;DR

This paper demonstrates that many-body effects in graphene's electronic structure can be accurately modeled using a tight-binding approach combined with many-body perturbation theory, matching ab-initio results at a lower computational cost.

Contribution

It introduces a unified approach applying many-body perturbation theory to a tight-binding model for graphene, enabling efficient and accurate analysis of its electronic properties.

Findings

Excellent agreement with ab-initio results for optical conductivity near Dirac point and π plasmon energies.

Self-consistency in the model is crucial for capturing Fermi velocity divergence.

Results are robust against doping and dielectric environment variations.

Abstract

We show that the many-body features of graphene band structure and electronic response can be accurately evaluated by applying many-body perturbation theory to a tight-binding (TB) model. In particular, we compare TB results for the optical conductivity with previous ab-initio calculations, showing a nearly perfect agreement both in the low energy region near the Dirac cone ($\sim 100$ meV), and at the higher energies of the {\pi} plasmon ($\sim 5$ eV). A reasonable agreement is reached also for the density-density response at the Brillouin zone corner. With the help of the reduced computational cost of the TB model, we study the effect of self-consistency on the screened interaction (W) and on the quasi-particle corrections, a task that is not yet achievable in ab-initio frameworks. We find that self-consistency is important to reproduce the experimental results on the divergence of the Fermi velocity, while it marginally affects the optical conductivity. Finally, we study the robustness of our results against doping or the introduction of a uniform dielectric environment.