Critical points of condensation in Coulomb systems

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.