Density Functional Theory for Two-Dimensional Homogeneous Materials

We study Density Functional Theory models for systems which are translationally invariant in some directions, such as a homogeneous 2-d slab in the 3-d space. We show how the different terms of the energy are modified and we derive reduced equations in the remaining directions. In the Thomas–Fermi model, we prove that there is perfect screening, and provide decay estimates for the electronic density away from the slab. In Kohn–Sham models, we prove that the Pauli principle is replaced by a penalization term in the energy. In the reduced Hartree–Fock model in particular, we prove that the resulting model is well-posed, and give some properties of the minimizer.