Effect of particle size distribution on polydisperse hard disks

Abstract

Using Monte Carlo simulations, we systematically investigate the effect of particle size distribution on the phase behaviour of polydisperse hard disks. Compared with the commonly used Gaussian-like polydisperse hard disks [Commun. Phys. 2, 70 (2019)], we find that the phase behaviour of polydisperse hard-disk systems with lognormal and triangle distributions are significantly different. In polydisperse hard-disk systems of lognormal distributions, although the phase diagram appears similar to that of Gaussian-like polydisperse hard disks, the re-entrant melting of hexatic or solid phase can not be observed in sedimentation experiments. For polydisperse hard-disk systems of triangle distributions, the phase behaviour is qualitatively different from the Gaussian-like and lognormal distributions, and we can not reach any system of true polydispersity larger than 0.06, which is due to the special shape of the triangle distribution. Our results suggest that the exact particle size distribution is of primary importance in determining the phase behaviour of polydisperse hard disks, and we do not have a universal phase diagram for different polydisperse hard-disk systems.