Quantum Monte Carlo Calculation of the Binding Energy of Bilayer Graphene

TL;DR

This study uses diffusion quantum Monte Carlo methods to accurately calculate the interlayer binding energies of bilayer graphene, providing results consistent with experiments and aiding future theoretical modeling.

Contribution

First quantum Monte Carlo calculations of bilayer graphene's interlayer binding energy, improving accuracy and informing functional development.

Findings

Binding energies: 11.5(9) and 17.7(9) meV/atom for AA and AB stacking

Predicted phonon frequency matches experimental data

Results support development of better van der Waals functionals

Abstract

We report diffusion quantum Monte Carlo calculations of the interlayer binding energy of bilayer graphene. We find the binding energies of the AA- and AB-stacked structures at the equilibrium separation to be 11.5(9) and 17.7(9) meV/atom, respectively. The out-of-plane zone-center optical phonon frequency predicted by our binding-energy curve is consistent with available experimental results. As well as assisting the modeling of interactions between graphene layers, our results will facilitate the development of van der Waals exchange-correlation functionals for density functional theory calculations.