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

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., CaCO 3 ). 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). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license

Parasitic crystallization of colloidal electrolytes: growing a metastable crystal from the nucleus of a stable phase

“…74) and on the assumption that a local order parameter can adequately distinguish between particles belonging to the stable and metastable phases, the popularity of Seeding for nucleation studies is sharply increasing. [102][103][104][105][106][107] Despite its approximations, Seeding has been shown to be consistent with independent calculations at moderate metastability using techniques like Umbrella sampling 50 or Forward flux sampling 51 as well as with non-biased calculations (i.e. brute force simulations) in the deep supercooled regime.…”

Solid–liquid interfacial free energy of ice Ih, ice Ic, and ice 0 within a mono-atomic model of water via the capillary wave method

“…coexistence and favourably compare these to predictions from the Turnbull correlation. It should be noted that improved fits to explicitly computed nucleation barriers have been reported when allowing the solid-liquid chemical potential difference to deviate from the bulk value, both for mW ice 3 and simple lattice models, 47 i.e., a value of γ 0 consistent with the usual assumptions of CNT may not be optimal.…”

Nominal vs. actual supersaturation of solutions

“…With Eqs. (13), (12), (10), (11) and (7) in mind, after some algebra one can express the nominal supersaturation (2) as follows:…”