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SUMMARY:Modelling non-classical mechanisms of crystal nucleation and growt
 h - David Quigley\, Warwick University
DTSTART:20110609T131500Z
DTEND:20110609T141500Z
UID:TALK30404@talks.cam.ac.uk
CONTACT:Dr G Moller
DESCRIPTION:\nCrystal growth is an important topic in materials science\, 
 chemical manufacturing\, biology and even medicine. Much of our molecular 
 scale understanding of crystal growth is anchored in classical nucleation 
 theory. In this simple picture\, solid clusters spontaneously shrink and g
 row until a single crystallite reaches a critical radius\, and is subseque
 ntly able to reach macroscopic size. Extended theories for polymorphism\, 
 such as Ostwald's rule of stages or the conjecture of Stranski and Totoman
 ow have proven successful in some simple systems.\n\nDespite these success
 es\, an increasingly large body of evidence suggests that nature can explo
 it non-classical pathways to control crystallisation in ways that cannot b
 e achieved synthetically. For example growth via amorphous precursors and 
 evidence of "stable pre-nucleation clusters" is reported in a number of mi
 neral systems.\n\nThis talk will discuss a number of ways in which compute
 r simulation can improve our understanding of non-classical crystal growth
 . In particular\, methods for overcoming the timescale limitations of mole
 cular dynamics will be discussed\, briefly illustrated with studies of ice
  nucleation\, and various examples from biomineralisation - the mechanism 
 by which nature manufactures shells\, teeth and bone. Simulations will als
 o be presented which demonstrate that nucleation barriers can emerge entir
 ely as a consequence of pH\, with no requirement for an interfacial free e
 nergy penalty between the growing crystal and its surroundings.
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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