Exciting imperfection : real structure effects in magnesium cadmium and zinc oxide Computational condensed matter physics as a branch of modern solid state physics comprises the field of ab initio calculations. Nowadays challenging parameter free studies can be carried out that deal with the many body aspects due to the involved electron electron interaction. Theoretical spectroscopy techniques provide insight into electronic excitations paving the way towards computer aided materials design e.g. for photovoltaics. In this thesis the transparent conductive oxides MgO ZnO and CdO are investigated; they are important materials for transparent oxide electronics. Initially a hybrid functional is used to model exchange and correlation. Subsequently quasiparticle energies are calculated using Hedins GW approximation of the electronic self energy. This leads to band structures densities of states spin orbit splittings effective band masses and natural band discontinuities. Solving a Bethe Salpeter equation for the optical polarization function yields the complex dielectric function including excitonic and local field effects. All underlying atomic geometries result from density functional theory based on local or semi local approximations to exchange and correlation.