  Folded regions are commonly encountered in a number of hexagonal boron
nitride (h-BN) based bulk and nanostructured materials. Two types of structural
modifications occur in folded h-BN layers: local curvature at the folded edges
and interlayer shear of the layers which changes the stacking of the
overlapping flat regions. In this work we discuss, via density functional
theory simulations, the impact of these structural modifications on the ground
state electronic structure of the pristine monolayer. We show that, depending
on the fold orientation, the overlapping region might present different
stacking configurations with subsequent variations of the fundamental band gap;
further gap changes occur at the folded regions. The overall electronic
structure of a BN folded monolayer can finally be described as a type-II
junction between two wide gap semiconductors located at the curved and flat
overlapping zones.
