This tutorial shows several calculations of NiO in the crystal-field approximation. Within the crystal-field approximation the solid is approximated by a single atom in an effective electric potential. This is a huge simplification and for many properties not valid. One should not confuse the crystal field potentials with real potentials. They are introduced to mimic the bonding in a crystal. Non-the-less it is a rather useful approximation for many local properties of a solid. Local moments, orbital occupation and several core level spectra can be well described to some extend on this level of theory. The most important part though is that the local symmetry can be reproduced, thereby the theory captures degeneracies and local multiplets.
This tutorial compares calculated spectra to experiment. In order to make the plots you need to download the experimental data. You can download them in a zip file here nio_data.zip. Please unpack this file and make sure to have the folders NiO_Experiment and NiO_Radial in the same folder as you do the calculations. And as always, if used in a publication, please cite the original papers that published the data.