Mitosis method for directly calculating the interfacial free energy of nuclei

N Duff and B Peters, MOLECULAR SIMULATION, 36, 498-504 (2010).

DOI: 10.1080/08927022.2010.483684

Nucleation from solution is an important first step in many natural and industrial phase transformations. In contrast to nucleation in pure component systems, the nucleation of solutes from solution remains a major challenge for simulation. The challenge stems from difficulty in inserting solutes to maintain an excess solute chemical potential in solution as the pre-critical nucleus grows. We present a 'mitosis' method to estimate the effective interfacial free energy of nanoscale nuclei in solution. The new method circumvents the need for controlling chemical potential by particle insertion, and thus it can provide insight on real crystal nucleation processes in explicit solvents. To test the new mitosis method, we demonstrate it on the Potts lattice gas model of nucleation from solution. This lattice model enables an alternative method for computing the interfacial free energy that has been used in simulations of nucleation in pure component systems. The two methods for computing the interfacial free energy agree to within 6%. This confirms that the mitosis method is a viable approach for computing the interfacial free energy of solute nuclei in real solutions. The method should facilitate a molecular level understanding of how solvents and additives influence nucleation rates and polymorph selection.

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