The physics of solid state chemistry

Abstract

Between the extremes of a chemist's empirical observation of chemical trends and a physicist's a priori calculations of energy bands lies the possibility of simple approximate model calculations of solid-state properties. Those which relate the bonding properties to the underlying electronic structure of specific systems are a part of solid-state chemistry. Such theories are less accurate than empirical interpolation where sufficient data exist, but provide intuitive understanding and allow calculations beyond the range of existing experiments. They are also less precise than a priori calculations, which however only move with difficulty beyond calculations of the energy bands themselves.

In simple metals the basis for such theory was provided by pseudopotential perturbation theory. In covalent and ionic solids LCAO theory seems more successful We discuss how a single set of atomic and interatomic LCAO parameters can provide elementary predictions of almost the entire range of properties of covalent and ionic solids. We see in particular how to estimate electronic energy levels in heterogeneous systems and at surfaces. We also explore questions related to effective charges and to angular rigidity, with emphasis on ionic solids. The concepts of ion softening and the chemical grip are useful in describing the corresponding numerical calculations.

Supported by the National Science Foundation through Grant DMR73-02351