Theoretical issues in electronic structure of the passivation layer

In this paper we review some fundamental concepts from the study of the physics of ordered oxides and of disordered metals. The passivation layer is a disordered oxide and thus requires mastery of both sets of concepts. We present some recent results on a model of highly disordered TiO₂ which illustrates some of these ideas. In summary we discuss ways in which the possibility of metal-insulator transitions in the passivation layer can be further explored theoretically and experimentally.