Editing Dispersion relation (section)

===Electron band structure===
In the study of solids, the study of the dispersion relation of electrons is of paramount importance. The periodicity of crystals means that many [[Fermi surface|levels of energy]] are possible for a given momentum and that some energies might not be available at any momentum. The collection of all possible energies and momenta is known as the [[band structure]] of a material. Properties of the band structure define whether the material is an [[Electrical insulation|insulator]], [[semiconductor]] or [[Conductor (material)|conductor]].