Nuclear Tunnelling and Dynamical Jahn-Teller Effect in Graphene with Vacancy

TL;DR

This paper investigates the dynamical Jahn-Teller effect in graphene with a vacancy, revealing significant nuclear tunnelling that affects electronic states and can be observed experimentally.

Contribution

It provides the first computational analysis of the tunnelling splitting and dynamical Jahn-Teller effect in vacancy-defected graphene.

Findings

Large tunnelling splitting of about 86 cm$^{-1}$ was calculated.

The vacancy induces a delocalization of nuclear wave functions.

The effects are observable in electron paramagnetic resonance experiments.

Abstract

We show that the substitutional vacancy in graphene forms a dynamical Jahn-Teller center. The adiabatic potential surface resulting from the electron-lattice coupling was computed using density-functional methods and subsequently the Schr\"odinger equation was solved for the nuclear motion. Our calculations show a large tunnelling splitting $3 \Gamma$ of about 86 cm$^{-1}$. %, which is large as compared to the typical strain splitting. The effect results in a large delocalization of the carbon nuclear wave functions around the vacancy leading to a significant broadening of the Jahn-Teller active $sp^2\sigma$ electron states. The tunnelling splitting should be observable in electron paramagnetic resonance and two-photon resonance scattering experiments.