The '''Empty Lattice Approximation''' is a theoretical [[electronic band structure]] model in which the '''potential''' is defined not more precisely than '''periodic''' and it is assumed that the potential is '''weak'''. The Empty Lattice Approximation isdescribes a descriptionnumber of the properties energy dispersion relations of electrons in an [[Fermi gas|electron gas]] of non-interacting [[Free electron model|'''free electrons''']] that move through a weak periodic potential of a '''[[crystal structure|crystal lattice]]'''. The energy of the electrons in the "empty lattice" is the same as the energy of free electrons. The model mainly serves to illustrate a number of features of energy dispersion relations in solids that are fundamental to all electronic band structures.
