Critical points of condensation in Coulomb systems
Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, ul. Izhorskaya 13/19, Moscow, 127412, Russian Federation
The critical points of condensation in Coulomb systems are described here by a modified van der Waals equation of state taking into account a many-particle exchange interaction between virtual atoms with overlapping classically accessible spheres of valence electrons. A characteristic feature of the Coulomb critical points is strong electron-ion coupling caused by the proximity to the metal-insulator transition. We consider a cell model of the exchange interaction of virtual atoms and examples of Coulomb critical points in a system of charged hard spheres, in alkali metals, in metal-ammonia solutions, and in excitonic systems. The Coulomb critical point parameters of transition metals are determined. We consider examples of insulator-metal transitions in semiconducting and dielectric fluids which form the Coulomb systems only in the liquid phase, and discuss a semiconducting critical state of mercury.