The EXP pair-potential system. I. Fluid phase isotherms, isochores, and quasiuniversality

Andreas Kvist Bacher, Thomas Schrøder, Jeppe Dyre

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Abstract

It was recently shown that the exponentially repulsive EXP pair potential defines a system of particles in terms of which simple liquids’ quasiuniversality may be explained [A. K. Bacher et al., Nat. Commun. 5, 5424 (2014); J. C. Dyre, J. Phys.: Condens. Matter 28, 323001 (2016)]. This paper and its companion [A. K. Bacher et al., J. Chem. Phys. 149, 114502 (2018)] present a detailed simulation study of the EXP system. Here we study how structure monitored by the radial distribution function and dynamics monitored by the mean-square displacement as a function of time evolve along the system’s isotherms and isochores. The focus is on the gas and liquid phases, which are distinguished pragmatically by the absence or presence of a minimum in the radial distribution function above its first maximum. A constant-potential-energy (NVU)-based proof of quasiuniversality is presented, and quasiuniversality is illustrated by showing that the structure of the Lennard-Jones system at four state points is well approximated by those of EXP pair-potential systems with the same reduced diffusion constant. Paper II studies the EXP system’s isomorphs, focusing also on the gas and liquid phases.
Original languageEnglish
Article number114501
JournalJournal of Chemical Physics
Volume149
Issue number11
Number of pages15
ISSN0021-9606
DOIs
Publication statusPublished - 18 Sep 2018

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