Effect of Energy Polydispersity on the Nature of Lennard-Jones Liquids

Trond Ingebrigtsen, Hajime Tanaka

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Abstract

In the companion paper [Ingebrigtsen, T. S.; Tanaka, H. J. Phys. Chem. B 2015, 119, 11052] the effect of size polydispersity on the nature of Lennard-Jones (LJ) liquids, which represent most molecular liquids without hydrogen bonds, was studied. More specifically, it was shown that even highly size polydisperse LJ liquids are Roskilde-simple (RS) liquids. RS liquids are liquids with strong correlation between constant volume equilibrium fluctuations of virial and potential energy and are simpler than other types of liquids. Moreover, it was shown that size polydisperse LJ liquids have isomorphs to a good approximation. Isomorphs are curves in the phase diagram of RS liquids along which structure, dynamics, and some thermodynamic quantities are invariant in dimensionless (reduced) units. In this paper, we study the effect of energy polydispersity on the nature of LJ liquids. We show that energy polydisperse LJ liquids are RS liquids. However, a tendency of particle segregation, which increases with the degree of polydispersity, leads to a loss of strong virial-potential energy correlation but is mitigated by increasing temperature and/or density. Isomorphs are a good approximation also for energy polydisperse LJ liquids, although particle-resolved quantities display a somewhat poorer scaling compared to the mean quantities along the isomorph.
Original languageEnglish
JournalJournal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical
Volume120
Issue number31
Pages (from-to)7704-7713
Number of pages10
ISSN1520-6106
DOIs
Publication statusPublished - 2016

Keywords

  • Fluids
  • Energy
  • Isotherms
  • Liquids
  • Physical and chemical properties

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