Chapter 1 Overview: A Standard Model of Solids

Abstract

Publisher Summary This chapter presents an overview of a standard model of solids. In constructing a model or picture of a solid, the view of reductionism proposes that: (1) because a solid is made of interacting atoms, (2) because of the length and energy scales involved, and (3) the dominant interaction is electromagnetism, for the determination of the electronic structure of solids, one should start with free atomic states and then determine the effects arising from atom–atom interactions. This model is particularly suited to systems where the atom-atom interactions are weak and can be treated quantum mechanically with perturbation theory. A specific model presently in use that derives from these ideas, is the tight-binding model (TBM), which is appropriate when the overlapping of electron wave functions of different atoms is small. The TBM can be extended to cases where there is considerable overlap; but, for enough overlap, it is best to consider the valence electrons as liberated from individual atoms. This nearly free electron model (NFEM) is more appropriate for a large class of solids.