  First Principles calculations are performed on the cubic bulk and its (001)
surface of CsPbBr3 to reveal its electronic and optoelectronic properties.
Various calculation schemes like GGA, GGA+SOC and the highly accurate modified
Becke Johnson potential (mBJ) are applied. The electronic energy band gap
calculations obtained from mBJ shows close approximity with the available
experimental results. The cubic bulk phase is investigated for its mechanical
stability and is found to bypass other structural phases. The optical
absorption of both the bulk and the surface surpasses non-lead based cubic
halides and zinc-based organic-inorganic hybrids.
