  Current interest in two-dimensional materials extends from graphene to others
systems like single-layer hexagonal boron-nitride (h-BN), for the possibility
of making heterogeneous structures to achieve exceptional properties that
cannot be realized in graphene.The electrically insulating h-BN and semi-metal
graphene may open good opportunities to realize a semiconductor by manipulating
the morphology and composition of such heterogeneous structures.Here we report
the mechanical properties of h-BN and its band structures tuned by mechanical
straining by using the density functional theory calculations.The elastic
properties, both the Young's modulus and bending rigidity for h-BN, are
isotropic.We reveal that there is a bi-linear dependence of band gap on the
applied tensile strains in h-BN. Mechanical strain can tune single-layer h-BN
from an insulator to a semiconductor, with a band gap in the 4.7eV to 1.5eV
range.
