The electrical conductivity of expanded liquid caesium

Abstract

Recently it has been shown that the nearly free electron model for describing the electrical, magnetic and optical properties of expanded liquid caesium has already broken down by the time three times the critical density is reached, i.e long before the transition from the metallic to the non-metallic state occurs, which seems to coincide with the critical point of the liquid-vapour phase transition (Tc=1924 K, pc=92 bar, rho c=0.38 g cm-3). The authors discuss the deviations from the nearly free electron model within the framework of a consistent quantum statistical approach to the electrical conductivity, which leads to a generalized Ziman formula, taking into account electron-electron scattering, arbitrary degeneracy and screening. Further possible mechanisms that might contribute to the behaviour of the electrical conductivity, such as the formation of bound states are also discussed.