We carry out ab initio calculations (LSDA, GGA, GW) for nickel oxide (NiO) to calculate its fundamental quasiparticle gap and magnetic moment. The electronic structure of NiO is a long standing problem. In particular, the orbital composition of the valence band maximum and the conduction band minimum from oxygen and nickel states is not fully understood. So far there have been two quasiparticle calculations on this important material, but due to computational difficulties, no fully-consistent calculation has been achieved. Our study will give more detailed insight into the origin and magnitude of the band gap in NiO.
