Condensed Matter Physics, 2015, vol. 18, No. 1, p. 13606
DOI:10.5488/CMP.18.13606           arXiv:1504.01224

Title: Heat capacity of liquids: A hydrodynamic approach
  T. Bryk (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv, Ukraine; Institute of Applied Mathematics and Fundamental Sciences, Lviv Polytechnic National University, 79013 Lviv, Ukraine) ,
  T. Scopigno (Dipartimento di Fisica, Universita di Roma La Sapienza, I-00185, Roma, Italy) ,
  G. Ruocco (Dipartimento di Fisica, Universita di Roma La Sapienza, I-00185, Roma, Italy; Center for Life Nano Science @Sapienza, Istituto Italiano di Tecnologia, 295 Viale Regina Elena, I-00161, Roma, Italy)

We study autocorrelation functions of energy, heat and entropy densities obtained by molecular dynamics simulations of supercritical Ar and compare them with the predictions of the hydrodynamic theory. It is shown that the predicted by the hydrodynamic theory single-exponential shape of the entropy density autocorrelation functions is perfectly reproduced for small wave numbers by the molecular dynamics simulations and permits the calculation of the wavenumber-dependent specific heat at constant pressure. The estimated wavenumber-dependent specific heats at constant volume and pressure, Cv(k) and Cp(k), are shown to be in the long-wavelength limit in good agreement with the macroscopic experimental values of Cv and Cp for the studied thermodynamic points of supercritical Ar.

Key words: liquids, thermodynamics, specific heat, hydrodynamic theory
PACS: 65.20.De, 61.20.Lc,

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