  We have predicted a new phase of nitrogen with octagon structure in our
previous study, which we referred to as octa-nitrogene (ON). In this work, we
make further investigation on its electronic structure. The phonon band
structure has no imaginary phonon modes, which indicates that ON is dynamically
stable. Using ab initio molecular dynamic simulations, the structure is found
to stable up to 100K, and ripples that are similar to that of graphene is
formed on the ON sheet. Based on DFT calculation on its band structure, single
layer ON is a 2D large-gap semiconductor with a band gap of 4.7eV. Because of
inter-layer interaction, stackings can decrease the band gap. Biaxial tensile
strain and perpendicular electric field can greatly influence the band
structure of ON, in which the gap decreases and eventually closes as the
biaxial tensile strain or the perpendicular electric field increases. In other
words, both biaxial tensile strain and perpendicular electric field can drive
the insulator-to-metal transition, and thus can be used to engineer the band
gap of ON. From our results, ON has potential applications in the electronics,
semiconductors, optics and spintronics, and so on.
