  We report the electronic structure of monoclinic CuO as obtained from first
principles calculations utilizing density functional theory plus effective
Coulomb interaction (DFT + U) method. In contrast to standard DFT calculations
taking into account electronic correlations in DFT + U gave antiferromagnetic
insulator with energy gap and magnetic moment values in good agreement with
experimental data. The electronic states around the Fermi level are formed by
partially filled Cu 3$d_{x^2-y^2}$ orbitals with significant admixture of O
2$p$ states. Theoretical spectra are calculated using DFT + U electronic
structure method and their comparison with experimental photoemission and
optical spectra show very good agreement.
