My research is focused on systems of interacting electrons. Such systems can be studied using high-throughput calculations which are mostly based on density-functional theory (DFT). DFT tells us that all observables are functionals of the ground state electronic density. However, the exact functionals are not known and one has to find approximations. The aim of my PhD was to develop explicit density functionals using connector approach. The power of this new approach is to profit from calculations that are performed once and for all in model systems.