The relative orientation of successive sheets, i.e. the stacking sequence, in
layered two-dimensional materials is central to the electronic, thermal, and
mechanical properties of the material. Often different stacking sequences have
comparable cohesive energy, leading to alternative stable crystal structures.
Here we theoretically and experimentally explore different stacking sequences
in the van der Waals bonded material hexagonal boron nitride (h-BN). We examine
the total energy, electronic bandgap, and dielectric response tensor for five
distinct high symmetry stacking sequences for both bulk and bilayer forms of
h-BN. Two sequences, the generally assumed AA' sequence and the relatively
unknown (for h-BN) AB (Bernal) sequence, are predicted to have comparably low
energy. We present a scalable modified chemical vapor deposition method that
produces large flakes of virtually pure AB stacked h-BN; this new material
complements the generally available AA' stacked h-BN
