On the choice of diameters in a polydisperse model glassformer: deterministic or stochastic?

Abstract

In particle-based computer simulations of polydisperse glassforming systems, the particle diameters $\sigma ={\sigma }_1,\dots ,{\sigma }_N$ of a system with $N$ particles are chosen with the intention to approximate a desired distribution density $f$ with the corresponding histogram. One method to accomplish this is to draw each diameter randomly from the density $f$. We refer to this stochastic scheme as model $\mathcal{S}$. Alternatively, one can apply a deterministic method, assigning an appropriate set of $N$ values to the diameters. We refer to this method as model $\mathcal{D}$. We show that especially for the glassy dynamics at low temperatures it matters whether one chooses model $\mathcal{S}$ or model $\mathcal{D}$. Using molecular dynamics computer simulation, we investigate a three-dimensional polydisperse non-additive soft-sphere system with $f(s)\sim s^{-3}$. The Swap Monte Carlo method is employed to obtain equilibrated samples at very low temperatures. We show that for model $\mathcal{S}$ the sample-to-sample fluctuations due to the quenched disorder imposed by the diameters $\sigma$ can be explained by an effective packing fraction. Dynamic susceptibilities in model $\mathcal{S}$ can be split into two terms: One that is of thermal nature and can be identified with the susceptibility of model $\mathcal{D}$, and another one originating from the disorder in $\sigma$. At low temperatures the latter contribution is the dominating term in the dynamic susceptibility.

arXiv comment15 pages, 11 figures

References in corpus (19)

• Supercooled Liquids for Pedestrians
• Probing the equilibrium dynamics of colloidal hard spheres above the mode-coupling glass transition
• Models and algorithms for the next generation of glass transition studies
• Spontaneous and induced dynamic fluctuations in glass-formers I: General results and dependence on ensemble and dynamics
• Hard Spheres: Crystallization and Glass Formation
• Fast Monte Carlo algorithm for supercooled soft spheres
• A Double-Transition Scenario for Anomalous Diffusion in Glass-Forming Mixtures
• Structural relaxation of polydisperse hard spheres: comparison of the mode-coupling theory to a Langevin dynamics simulation
• Pinching a glass reveals key properties of its soft spots
• Lengthscale dependence of dynamic four-point susceptibilities in glass formers
• Dynamic heterogeneity in a glass forming fluid: susceptibility, structure factor and correlation length
• Efficient swap algorithms for molecular dynamics simulations of equilibrium supercooled liquids
• Frequency dependent specific heat of viscous silica
• Importance of many-body correlations in glass transition: an example from polydisperse hard spheres
• Mechanical properties of simple computer glasses
• Impact of size polydispersity on the nature of Lennard-Jones liquids
• Random-field Ising model criticality in a glass-forming liquid
• On the overlap between configurations in glassy liquids
• Brittle yielding in supercooled liquids below the critical temperature of mode coupling theory

Cited by in corpus (1)

• Swap Monte Carlo for diatomic molecules