Ab-initio study of the effects induced by the electron-phonon scattering in carbon based nanostructures

TL;DR

This study uses first-principles methods to analyze how electron-phonon interactions affect the electronic properties of carbon nanostructures, revealing complex behaviors that challenge traditional approximations.

Contribution

It introduces a fully ab-initio dynamical approach within Many Body Perturbation Theory to accurately describe electron-phonon effects in nanostructures, surpassing conventional methods.

Findings

Electron-phonon interactions create complex structures in the electronic self-energy.

Quasi-particle picture and adiabatic approximations are inadequate for these systems.

Zero point motion significantly influences the electronic states at zero temperature.

Abstract

In this paper we investigate from first principles the effect of the electron-phonon interaction in two paradigmatic nanostructures: trans-polyacetylene and polyethylene. We found that the strong electron-phonon interaction leads to the appearance of complex structures in the frequency dependent electronic self-energy. Those structures rule out any quasi-particle picture, and make the adiabatic and static approximations commonly used in the well-established Heine Allen Cardona (HAC) approach inadequate. We propose, instead, a fully ab-initio dynamical formulation of the problem within the Many Body Perturbation Theory framework. The present dynamical theory reveals that the structures appearing in the electronic self-energy are connected to the existence of packets of correlated electron/phonon states. These states appear in the spectral functions even at $T=0\,K$, revealing the key role played by the zero point motion effect. We give a physical interpretation of these states by disclosing their internal composition by mapping the Many Body problem to the solution of an eigenvalue problem.