How complicated can crystal growth really be?
Prof Julian Gale
Curtin University, Australia
Biography
Julian Gale was awarded his first degree from University of Oxford where he also obtained his DPhil
in the Dept. of Chemical Crystallography. After a post-doctoral position at the Royal Institution of
Great Britain he moved to Imperial College London to take up a Royal Society University Research
Fellowship in the Department of Chemistry, where he subsequently became Reader in Theoretical
and Computational Chemistry. In 2003, Julian moved to Curtin University as one of two inaugural
Premier’s Research Fellows awarded by the Government of Western Australia where he also served
as acting director of the Nanochemistry Research Institute and as a member of the Premier’s Science
and Innovation Council. Currently he is an ARC Professorial Fellow in the Department of Chemistry
with Curtin’s Resources and Chemistry Precinct.
Authors
Raffaella Demichelis1, Paolo Raiteri2, Julian D. Gale3, Adam F. Wallace4, Jim De Yoreo5, Andrew G.
Stack6, Matthias Kellermeier7, Denis Gebauer8
1 NRI, Department of Chemistry, Curtin University, PO Box U1987, Perth, WA 6845,
[email protected]
2 NRI, Department of Chemistry, Curtin University, PO Box U1987, Perth, WA 6845,
[email protected]
3 NRI, Department of Chemistry, Curtin University, PO Box U1987, Perth, WA 6845,
[email protected]
4 The Molecular Foundry/Earth Sciences, Lawrence Berkeley National Laboratory, Berkeley, CA
94720, [email protected]
5 Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA,
[email protected]
6 Chemical Sciences Division, Oak Ridge National Laboratory, PO Box 2008, Tennessee 37831,
USA, [email protected]
7 Dept. of Physical Chemistry, University of Konstanz, Konstanz, Germany,
[email protected]
8 Dept. of Physical Chemistry, University of Konstanz, Konstanz, Germany, [email protected]
Abstract
Crystal growth is ubiquitous, both in the laboratory and the natural world. As a result there have been
theories to explain crystallisation that go back over a century, and have evolved along with our atomic
view of matter. Even after all this time, this field of research is still presenting challenges to our
understanding. In the case of calcium carbonate (CaCO3), one of the most widespread minerals at the
Earth’s surface, there has been considerable debate regarding the nucleation and growth
mechanisms. Firstly, it was recognised that in many natural systems crystalline polymorphs form via
an amorphous precursor phase, rather than by direct nucleation. Secondly, and most recently, the
existence of stable pre-nucleation clusters was proposed by Gebauer et al [1], in apparent
contravention of classical nucleation theory.
In this presentation computer simulation, based on molecular dynamics with a thermodynamically
accurate force field, will be used to probe the early and late stages of growth of calcium carbonate from
aqueous solution. In particular, the question of why the initial ion association is stable, and what the
form of these prenucleation clusters is, will be examined [2]. It will be shown that through careful
determination of the free energy landscape [3] it is possible to gain new insights into the complex
emergence of crystalline materials via multiple amorphous and liquid-like precursor states [4], as well
as how they grow subsequent to nucleation.
[1] D. Gebauer et al, Science, 322, 1819 (2008)
[2] R. Demichelis et al, Nature Commun., 2, 590 (2011)
[3] A.G. Stack et al, J. Am. Chem. Soc., 134, 11 (2012)
[4] A.F. Wallace et al, (in press)
Key Words
Crystal growth; simulation; calcium carbonate; molecular dynamics; nucleation