Calculation of the electronic structure of the Mott insulator NiO, LaMnO3 and of GaN:Mn

We have shown that energy values of the d - d splittings of 2.06 eV in LaMnO3 and 1.41 eV in Mn-doped GaN can be consistently explained within the ordinary crystal-field theory. We claim that the d - d splitting is of the (almost) purely electrostatic origin and it has been calculated from first principles. Finally, contrary to the band-theory, we claim the existence of the discrete electronic structure, in a meV scale, in 3d-atom containing compounds.