ELECTRONIC TRANSPORT
TRANSPORT PROPERTIES OF LIQUID NON-SIMPLE METALS

Abstract
We discuss the theoretical approaches to the transport properties of liquid non-simple the scattering potentials are strong. To this category belong liquid transition metals and their alloys, rare earth metals, expanded metallic fluids, etc. For these metals, the picture of nearly free electrons being weakly scattered by neutral pseudo-atoms is not plausible and accordingly the Ziman theory for the electrical resistivity is no longer justified. Although a naive extension of the original Ziman theory to the strong-scattering systems has been proposed, no satisfactory grounds for the so-called extended Ziman formula have been given. It is required therefore to establish a systematic scheme of studying the transport properties of these metals from first principles. One promising way to this end is to extend and apply to the problem the theoretical methods so far developed to examine one-electron properties such as the density of states and spectral functions. In the course of extension, we emphasize the importance of the basic conservation laws such as embodied by the generalized optical theorem. Among various methods, the effective medium approximation (EMA), which has been shown to be the best single-site theory for one-electron properties, also serves as a good first approximation for the conductivity. The EMA and other theories are applied to the tight-binding model and the muffin-tin potential model. Moreover, the s-d hibridization model is appropriate to describe the situation as is found in liquid transition metals where the nearly-free s-electrons and the tightly-bound d-electrons are both present. Our philosophy underlying these theories and the formulations are briefly given, and the applications to liquid transition metals and expanded mercury are demonstrated.