title: Equation of states for classical Coulomb systems: use of the Hubbard-Schofield approach.
abstract: An effective method based on the Hubbard-Schofield approach [Phys. Lett. A 40, 245 (1972)] is developed to calculate the free energy of classical Coulomb systems. This method significantly simplifies the derivation of the cluster expansion. A diagrammatic representation of the cluster integrals is proposed. Simple rules providing the leading order in density n of each diagrammatic contribution are found. We calculate the n(3) contribution and recover the results at the order n(5/2) obtained by the traditional method of resummation of diverging Mayer bonds.
authors.affiliation: Institut für Physik, Humboldt Universität Berlin, Invalidenstrasse 110, 10115 Berlin, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Ortner