Toward accurate modeling of structure and energetics of bulk hexagonal boron nitride

Abstract

Materials that exhibit both strong covalent and weak van der Waals interactions pose a considerable challenge to many computational methods, such as DFT. This makes assessing the accuracy of calculated properties, such as exfoliation energies in layered materials like hexagonal boron nitride (h-BN) problematic, when experimental data are not available. In this paper, we investigate the accuracy of equilibrium lattice constants and exfoliation energy calculation for various DFT-based computational approaches in bulk h-BN. We contrast these results with available experiments and reference fixed-node diffusion quantum Monte Carlo (QMC) results. From our reference QMC calculation, we obtained an exfoliation energy of $-33\pm$ 2 meV/atom (-0.38 $\pm$ 0.02 J/m ${}^2$ ).

Keywords: DFT; exfoliation energy; h-BN; quantum Monte Carlo; van der Waals.