The Electronic and Cohesive Properties of Disordered Simple Metals

Abstract

Simple metals are those without d or f electrons in the conduction band and whose core levels lie at energies well below the conduction band. For these metals it is reasonable to assume that the core electrons are rigidly fixed to the nuclei so that an elemental metal can be well-represented by a two component system of N ions and NZ ’conduction’ electrons where Z is the usual chemical valence. The alkalis, Be, Mg, Zn, Cd, Hg, Al, Ga, In, Sn, Tl and Pb are usually described as simple metals. The outer electronic structure of these metals is characterized by extended s and p like states and, to some extent, can be said to be nearly-free-electron like. The alkaline earths Ca, Sr and Ba have unfilled d bands and their hybridisation with the nearly-free s-p bands has significant effects on the electronic structure in the neighbourhood of the Fermi energy. Consequently, the alkaline earths can be considered intermediate between simple and transition metals. The latter, of course, have unfilled d states at the Fermi energy.