Many of the questions below can be answered by experimenting with the theory. If you turn off successively interactions (Exchange interaction, Ni-3d spin-orbit coupling, 2p-3d Coulomb interaction, 3-d Coulomb interaction, ...) you can find which interactions are responsible for the effect we describe. Combining this with looking at the right expectation values (including partial excitations and spectroscopy in tensor form) can give insight into the physics behind the observation. Good luck

*) Compare the value of the Slater integrals between the Ni 1s and Ni 3d orbital to the Slater integrals between the Ni 3s and Ni 3d orbital. Why is there such a big difference and what does this mean for the spectroscopy on these different edges? 

*) X-ray absorption at the Ni L23 edge is very similar when calculated on a ligand field or crystal field level. Core level photoemission at this same edge is rather different in the crystal field and ligand field theory. Why is this the case? 

*) Calculate the gap (energy cost to add an electron into the lowest state plus the energy to remove an electron from the lowest state) in NiO. Once within the crystal field approximation and once in the Ligand field approximation. Why are they different and wich parameter determines the gap?





