ABSTRACT
In this chapter, we shall consider the problem of electrons in solid state ionics. The electron problem is different from the phonon problem discussed in the last chapter. In the phonon problem, there are no counterparts of ion motion (elastic led) outside the rst Brillouin zone (BZ). In the electron problem that is akin to the x-ray diffraction problem discussed in Chapter 4, the electromagnetic eld is omnipresent in the crystal and not just in the ions.
