Communication: Pair interaction ordering in fluids with random interactions

Abstract

We use molecular dynamics simulations in 2D to study multi-component systems in the limiting case where all the particles are different (APD). The particles are assumed to interact via Lennard-Jones potentials, with identical size parameters but their pair interaction parameters are generated at random from a uniform or from a peaked distribution. We analyze both the global and the local properties of these systems at temperatures above the freezing transition and find that APD fluids relax into a non-random state characterized by clustering of particles according to the values of their pair interaction parameters (particle-identity ordering).

Neighborhood Identity Ordering and Quenched to Annealed Transition in Random Bond Models

“…The most important result of the MD simulations [3] is that, upon cooling, there is ordering not only of the centers of the mass of the particles, but also of the identities of neighboring particles: as the temperature is decreased, the system lowers its energy by choosing neighboring particles in a non-random fashion that depends on the distribution of interaction strengths and on the temperature. We call this transition from random neighbors to specific neighbors the neighborhood identity ordering (NIO) transition.…”

“…A previous paper coauthored by us [3] has reported the results of molecular dynamics (MD) simulations on a system of particles where the interaction strength between the particles was chosen randomly from some distribution. These systems, which we termed all particles are different (APD), include a multiplicity of different interaction strengths, even though they have the same Lennard-Jones form of the pair interaction potential..…”

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

“…(2): σ and ǫ ij set, respectively, the length and energy scale of the pair interaction between particle i and particle j (i,j = 1, ..., N ). The pair interaction energy ǫ ij is assigned according to the rule 41,46 …”

“…An energy distribution has in previous studies been applied together with, e.g., a distribution in the molecular size 12,40 , and only very recently been studied isolated for its interesting phase behavior [41][42][43] . To fully unravel the relative effects of polydispersity on strong virial-potential energy correlation we focus, in this study, on energy polydisperse LJ liquids 41 .…”

“…To fully unravel the relative effects of polydispersity on strong virial-potential energy correlation we focus, in this study, on energy polydisperse LJ liquids 41 . Although this system is less experimentally realizable than size polydisperse systems, we believe that the conclusions drawn from this kind of study are necessary for understanding the effect of polydispersity on the nature of LJ liquids.…”