The first theoretical description of FOs is rooted in these considerations. Jacques Friedel 1 considered metallic alloys and how their parameters can be described in terms of their electronic structure model. As the standard Thomas-Fermi approximation (classical screening effect resulting in the charge density decaying exponentially from the defect) overestimates the resistivity of the Cu alloys by at least an order of magnitude, he considered the quantum approximation based on the von Laue theorem : the free electron gas density ϱ(E, r) -density at point r of electrons with energy at most E -is independent of the boundary conditions as long as the point r is far enough from the boundary surface.