ABSTRACT
In this chapter we shall approach the description of electrons in solids using one of the simplest models possible, that of electrons as classical particles moving almost freely within the material experiencing minimal interactions with the ionic potential. In fact, the model assumes that the ionic potential is completely flat, and that the only constraints on electron motion, apart from electron-electron collisions, are provided by the physical boundary of the material. At first, such a model seems so far from reality as to be probably of little use; however, quite surprisingly the model can give some useful insights and provides an initial description of electrical and thermal conductivity, the Hall effect and the Wiedemann-Franz law. Nevertheless, this classical model has no way of distinguishing between conductors and insulators and gives an incorrect prediction of the heat capacity of the electrons, so that ultimately a more comprehensive model is needed.
