Stacking in bulk and bilayer hexagonal boron nitride.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Layered hexagonal boron nitride (h-BN) is a crucial material with unique electronic and mechanical properties.
• Understanding interlayer interactions is vital for predicting and controlling the behavior of 2D materials.

Purpose of the Study:

• To investigate the stacking orders and interlayer interactions in hexagonal boron nitride bulk and bilayers.
• To determine the most stable stacking configuration and the energy barrier for sliding.

Main Methods:

• Utilized high-level ab initio theory, specifically local second-order Møller-Plesset perturbation theory (LMP2).
• Analyzed electrostatic and London dispersion interactions contributing to interlayer forces.

Main Results:

• Identified AA' stacking as the most stable configuration for h-BN bilayers.
• Quantified the minimum energy sliding path, revealing a low energy barrier of 3.4 meV per atom.
• Found that standard density functionals often fail to accurately predict interlayer energies, unlike a specific PBE functional.

Conclusions:

• Electrostatic and London dispersion forces are key drivers of interlayer distance and stacking order in h-BN.
• The AA' stacking configuration is energetically favored, with minimal energy required for sliding.
• Accurate theoretical prediction of h-BN interlayer energies requires advanced methods or specific functionals, aligning well with experimental findings.