The Stacking in Bulk and Bilayer Hexagonal Boron Nitride

TL;DR

This study uses advanced ab initio methods to analyze stacking orders in hexagonal boron nitride, revealing the importance of electrostatic and dispersion interactions, with AA' being the most stable configuration.

Contribution

It provides high-accuracy LMP2 calculations showing the dominant interactions and corrects the limitations of common density functionals in describing interlayer energies.

Findings

AA' stacking is the most stable configuration.

The energy barrier for sliding is 3.4 meV per atom.

PBEsol functional agrees well with LMP2 and experimental data.

Abstract

The stacking orders in layered hexagonal boron nitride bulk and bilayers are studied using high-level ab initio theory (local second-order Moller-Plesset perturbation theory, LMP2). Our results show that both electrostatic and London dispersion interactions are responsible for interlayer distance and stacking order, with AA' being the most stable one. The minimum energy sliding path includes only the AA' high-symmetry stacking, and the energy barrier is 3.4 meV per atom for the bilayer. State-of-the-art Density-functionals with and without London dispersion correction fail to correctly describe the interlayer energies with the exception of PBEsol that agrees very well with our LMP2 results and experiment.