title: Crystallization and aging in hard-sphere glasses.
abstract: We report new results from our programme of molecular dynamics simulation of hard-sphere systems, focusing on crystallization and glass formation at high concentrations. First we consider a much larger system than hitherto, N = 86 400 equal-sized particles. The results are similar to those obtained with a smaller system, studied previously, showing conventional nucleation and growth of crystals at concentrations near melting and crossing over to a spinodal-like regime at higher concentrations where the free energy barrier to nucleation appears to be negligible. Second, we investigate the dependence on the initial state of the system. We have devised a Monte Carlo 'constrained aging' method to move the particles in such a way that crystallization is discouraged. After a period of such aging, the standard molecular dynamics programme is run. For a system of N = 3200, we find that constrained aging encourages caging of the particles and slows crystallization somewhat. Nevertheless, both aged and unaged systems crystallize at volume fraction φ = 0.61 whereas neither system shows full crystallization in the duration of the simulation at φ = 0.62, a concentration still significantly below that of random close packing.
authors.affiliation: SUPA, School of Physics and Astronomy, The University of Edinburgh, Edinburgh, UK. cvaleria@ph.ed.ac.uk
authors.forename: C
authors.initials: C
authors.lastname: Valeriani
authors.forename: E
authors.initials: E
authors.lastname: Sanz
authors.forename: E
authors.initials: E
authors.lastname: Zaccarelli
authors.forename: W C K
authors.initials: WC
authors.lastname: Poon
authors.forename: M E
authors.initials: ME
authors.lastname: Cates
authors.forename: P N
authors.initials: PN
authors.lastname: Pusey
mesh_terms: D003198:Computer Simulation; D003460:Crystallization; D005898:Glass / Q000737:chemistry*; D006244:Hardness; D008422:Materials Testing; D008863:Microspheres; D056004:Molecular Dynamics Simulation; D009010:Monte Carlo Method; D010316:Particle Size; D044367:Phase Transition; D013816:Thermodynamics; D013997:Time Factors