Nucleation barrier reconstruction via the seeding method in a lattice model with competing nucleation pathways

Lifanov, Yuri and Vorselaars, Bart and Quigley, David (2016) Nucleation barrier reconstruction via the seeding method in a lattice model with competing nucleation pathways. The Journal of Chemical Physics, 145 (21). p. 211912. ISSN 0021-9606

Full content URL: http://dx.doi.org/10.1063/1.4962216

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Abstract

We study a three-species analogue of the Potts lattice gas model of nucleation from solution in a
regime where partially disordered solute is a viable thermodynamic phase. Using a multicanonical
sampling protocol, we compute phase diagrams for the system, from which we determine
a parameter regime where the partially disordered phase is metastable almost everywhere in the
temperature–fugacity plane. The resulting model shows non-trivial nucleation and growth behaviour,
which we examine via multidimensional free energy calculations. We consider the applicability of the
model in capturing the multi-stage nucleation mechanisms of polymorphic biominerals (e.g., CaCO3).
We then quantitatively explore the kinetics of nucleation in our model using the increasingly popular
“seeding” method. We compare the resulting free energy barrier heights to those obtained via explicit
free energy calculations over a wide range of temperatures and fugacities, carefully considering the
propagation of statistical error. We find that the ability of the “seeding” method to reproduce accurate
free energy barriers is dependent on the degree of supersaturation, and severely limited by the use of
a nucleation driving force ∆µ computed for bulk phases. We discuss possible reasons for this in terms
of underlying kinetic assumptions, and those of classical nucleation theory. C 2016 Author(s)

Keywords:Chemical physics, JCOpen
Subjects:F Physical Sciences > F320 Chemical Physics
Divisions:College of Science > School of Mathematics and Physics
ID Code:24864
Deposited On:27 Oct 2016 14:25

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