In this thesis we study dynamic heterogeneity in glass-forming systems by means of kinetically constrained models (KC1\Is) and atomistic molecular dynamics simulations. KCr-Is are idealised models of supercooled liquids in which glassy dynamics are the result of local dynamical constraints. By studying a range of models with varying complexity we show that KC1\Is readily capture the key dynamical ingredients of supercooled liquids. Using the framework of r-Ionte Carlo with absorbing r-Iarkov Chains (r.ICAr-IC) we develop an advanced algorithm that can improve on traditional numerical methods by many orders of magnitude for the simulation of a particular KC1\1. \Ve use the two-vacancy assisted triangular lattice gas, or (2)-TLG, to investigate the relationship between structure and dynamics in a supercooled liquid. KCr-Is are used to help interpret recent atomistic simulations that consider supercooled dynamics in terms of transitions between low-energy configurations, or 'metabasins', of the potential energy landscape. Our results imply that dynamic facilitation may be a suitable mechanism for such transitions. We analyse distributions of persistence and exchange times in a computationally efficient atomistic model. For sufficient supercooling we observe a striking de-coupling behveen the two distributions, as previously predicted from KCr.Is. Finally, ,ve study the dynamics of KCr-Is under the influence of an external field, both in the form of confinement and a gravitational field. \Ve compare our results to recent experimental and numerical studies.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:491128 |
| Date | January 2007 |
| Creators | Hedges, Lester Owen |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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