Phase diagram of a polydisperse soft-spheres model for liquids and colloids

TL;DR

This study maps the phase diagram of polydisperse soft spheres, revealing how size dispersion influences phase transitions and suggesting that colloidal terminal polydispersity is driven by kinetic effects.

Contribution

It introduces an optimized Monte Carlo method to explore phase behavior in polydisperse systems below the glass transition, linking equilibrium phases to kinetic phenomena.

Findings

First order freezing transition observed across dispersions

Crystalline structures in low dispersion systems

Density inhomogeneities in highly disperse systems

Abstract

The phase diagram of soft spheres with size dispersion has been studied by means of an optimized Monte Carlo algorithm which allows to equilibrate below the kinetic glass transition for all sizes distribution. The system ubiquitously undergoes a first order freezing transition. While for small size dispersion the frozen phase has a crystalline structure, large density inhomogeneities appear in the highly disperse systems. Studying the interplay between the equilibrium phase diagram and the kinetic glass transition, we argue that the experimentally found terminal polydispersity of colloids is a purely kinetic phenomenon.