Large scale numerical simulations to understand and predict the properties of nanostructures

The demands on the numerical methods to calculate the electronic and optical properties of nanostructures are presented. It is emphasized that a connection to experimental results requires to take many atoms into account, while considering the effects of correlations in the excited exciton states. A modern approach to this difficult challenge is presented along with an application of the method to predict the feasibility of a scheme aimed at the generation of entangled photon pairs.