Authors: M.Cassandro,G.Gallavotti,J.L.Lebowitz,E.Monroe

Title: Exitence and uniqueness of equilibrium states for some spin and continoum systems
Communication in Mathematical Physics, 32, 153--165, 1973,

Abstract: The one to one correspondence between the existence of a unique equilibrium state and the differentiability of the free energy density with respect to the external field previously shown for Ising ferromagnets is extendend to higher valued spin systems as well as to continuum systems satisfying the Fortuin, Kasteleyn and Ginibre inequalities. In particular this is shown to hold for a mixture of A B particles in which there is no interaction between like particles and a repulsion between unlike particles. Where the derivative of the free energy is discontinuous there are at least two equilibrium states.

Key words:  Statistical Mechanics, Phase Rule, Phase Transitions, Thermodynamic Limit, Lattice Gas

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