  We use the many techniques of alloy theory to study antiferromagnetic NiO,
considered as an alloy of spin-up and spin-down Ni atoms. The questions are:
the true antiferromagnetic ground state and the possibility of obtaining
ferrimagnetic configurations. Further we use the GGA/LDA- 1/2 technique to
investigate the electronic excitation spectrum. We found two valence bands and
band gaps, of 4.0eV consistent with bremsstrahlung-isochromat-spectroscopy
(BIS) result, and 1.2eV consistent with the known 10Dq value for the Ni++ ion.
The features of a Mott insulator are presented without recurring to an
electron-pair correlation.
