Communication: Thermodynamics of condensed matter with strong pressure-energy correlations

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We show that for any liquid or solid with strong correlation between its NVT virial and potential-energy equilibrium fluctuations, the temperature is a product of a function of excess entropy per particle and a function of density, T = f(s)h(ρ). This implies that (1) the system's isomorphs (curves in the phase diagram of invariant structure and dynamics) are described by h(ρ)/T = Const., (2) the density-scaling exponent is a function of density only, and (3) a Grüneisen-type equation of state applies for the configurational degrees of freedom. For strongly correlating atomic systems one has h(ρ) = ∑nCnρn/3 in which the only non-zero terms are those appearing in the pair potential expanded as v(r) = ∑nvnr−n. Molecular dynamics simulations of Lennard-Jones type systems confirm the theory.
Original languageEnglish
JournalJournal of Chemical Physics
Issue number6
Pages (from-to)061102-1 - 061102-4
Number of pages4
Publication statusPublished - 2012

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