期刊
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
卷 367, 期 1909, 页码 4993-5011出版社
ROYAL SOC
DOI: 10.1098/rsta.2009.0181
关键词
hard spheres; crystallization; glass formation; polydispersity; molecular dynamics; colloid
资金
- eDIKT initiative
- UK Engineering and Physical Sciences Research Council [EP/E030173]
- European Union [MRTN-CT-2003-504712]
- SoftComp Network of Excellence [NMP3-CT-2004-502235]
- EPSRC Senior Fellowship [EP/D071070]
- Royal Society Research Professorship
- Engineering and Physical Sciences Research Council [EP/E030173/1] Funding Source: researchfish
- EPSRC [EP/E030173/1] Funding Source: UKRI
Motivated by old experiments on colloidal suspensions, we report molecular dynamics simulations of assemblies of hard spheres, addressing crystallization and glass formation. The simulations cover wide ranges of polydispersity s (standard deviation of the particle size distribution divided by its mean) and particle concentration. No crystallization is observed for s > 0.07. For 0.02 < s < 0.07, we find that increasing the polydispersity at a given concentration slows down crystal nucleation. The main effect here is that polydispersity reduces the supersaturation since it tends to stabilize the fluid but to destabilize the crystal. At a given polydispersity (< 0.07), we find three regimes of nucleation: standard nucleation and growth at concentrations in and slightly above the coexistence region; 'spinodal nucleation', where the free-energy barrier to nucleation appears to be negligible, at intermediate concentrations; and, at the highest concentrations, a new mechanism, still to be fully understood, which only requires small rearrangement of the particle positions. The cross-over between the second and third regimes occurs at a concentration, approximately 58 per cent by volume, where the colloid experiments show a marked change in the nature of the crystals formed and the particle dynamics indicate an 'ideal' glass transition.
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