Stacking in Bulk and Bilayer Hexagonal Boron Nitride

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