糖心TV

Speaker: David Quigley (糖心TV)

Title: Modelling non-classical mechanisms of crystal nucleation and growth

Abstract:

The growth of crystals from solution is an important step in the synthesis of many chemicals and materials. One route to lower-energy manufacture of materials, and to enhancing our control of material structure, is to direct and control the early stages of crystal nucleation.

The standard framework for understanding this process is classical nucleation theory. In this picture small, ordered clusters of solute spontaneously grow and re-dissolve until one such crystallite reaches a diameter from which it becomes energetically favourable to reach macroscopic size. This picture can be an extreme over-simplification. In particular biomineralisation (the process by which organisms grow shell, teeth and bone) can proceed via hydrated amorphous precursor phases and metastable partially disordered crystallites. Solution additives, proteins and organic scaffolds exert influence on the choice of growth mechanism.

This talk will review progress in molecular scale modelling of biomineralisation, focussing on recent work which proposes a mechanism for forming stable precritical clusters of calcium carbonate [1]. Using large scale simulations with accurate atomistic models, these have been established as polymer-like aggregation of ions [2]. A rigorous study of this model at the level of statistical thermodynamics would be prohibitively expensive, leading to interest in capturing non-classical nucleation in simple "toy" models. One such model will be reviewed, with a view to future studies aimed at capturing partial disorder and stable pre-nucleation behaviour.

[1] Gebauer, Volkel and Colfen, Science 322, 1819 (2008).
[2] Demichelis, Raiteri, Gale, Quigley and Gebauer, Nature Communications 2, 590 (2011).
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Lunch: Group 1