Heterogeneous nucleation in the low-barrier regime

Scheifele, Benjamin; Saika‐Voivod, Ivan; Bowles, Richard K.; Poole, Peter H.

doi:10.1103/physreve.87.042407

Cited by 18 publications

(20 citation statements)

References 50 publications

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“…Defined in this way, ∆G * represents the work required to bring the caged particle into the transition state from anywhere in the cage and, as such, it will always be positive because the configuration space of the transition state is a restricted subset of all the possible configurations available to the system. Identifying the entire configuration space of the "reactive region" as the appropriate reference state leads to a significant improvement in the predicted rates using TST in activated process as shown in the case of heterogeneous nucleation [58].…”

Section: B a Transition State Theory For Hopping Timesmentioning

confidence: 99%

Diffusion in quasi-one-dimensional channels: A small system n, p, T, transition state theory for hopping times

Ahmadi

Bowles

2017

The Journal of Chemical Physics

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Particles confined to a single file, in a narrow quasi-one dimensional channel, exhibit a dynamic crossover from single file diffusion to Fickian diffusion as the channel radius increases and the particles can begin to pass each other. The long time diffusion coefficient for a system in the crossover regime can be described in terms of a hopping time, which measures the time it takes for a particle to escape the cage formed by its neighbours. In this paper, we develop a transition state theory approach to the calculation of the hopping time, using the small system isobaric-isothermal ensemble to rigorously account for the volume fluctuations associated with the size of the cage. We also describe a Monte Carlo simulation scheme that can be used to calculate the free energy barrier for particle hopping. The theory and simulation method correctly predict the hopping times for a two dimensional confined ideal gas system and a system of confined hard discs over a range of channel radii, but the method breaks down for wide channels in the hard discs case, underestimating the height of the hopping barrier due to the neglect of interactions between the small system and its surroundings.

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Section: B a Transition State Theory For Hopping Timesmentioning

confidence: 99%

Diffusion in quasi-one-dimensional channels: A small system n, p, T, transition state theory for hopping times

Ahmadi

Bowles

2017

The Journal of Chemical Physics

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“…(16) This is incorrect in terms of rate prediction, as it fails to account for the phase space available in the free energy basin around n min [40].…”

Section: B Nmax As the Order Parametermentioning

confidence: 99%

Crystallization of Lennard-Jones nanodroplets: From near melting to deeply supercooled

Malek

Morrow

Saika‐Voivod

2015

The Journal of Chemical Physics

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We carry out molecular dynamics (MD) and Monte Carlo (MC) simulations to characterize nucleation in liquid clusters of 600 Lennard-Jones particles over a broad range of temperatures. We use the formalism of mean first-passage times to determine the rate and find that Classical Nucleation Theory (CNT) predicts the rate quite well, even when employing simple modelling of crystallite shape, chemical potential, surface tension and particle attachment rate, down to the temperature where the droplet loses metastability and crystallization proceeds through growth-limited nucleation in an unequilibrated liquid. Below this crossover temperature, the nucleation rate is still predicted when MC simulations are used to directly calculate quantities required by CNT. Discrepancy in critical embryo sizes obtained from MD and MC arises when twinned structures with five-fold symmetry provide a competing free energy pathway out of the critical region. We find that crystallization begins with hcp-fcc stacked precritical nuclei and differentiation to various end structures occurs when these embryos become critical. We confirm that using the largest embryo in the system as a reaction coordinate is useful in determining the onset of growth-limited nucleation and show that it gives the same free energy barriers as the full cluster size distribution once the proper reference state is identified. We find that the bulk melting temperature controls the rate, even though the solid-liquid coexistence temperature for the droplet is significantly lower. The value of surface tension that renders close agreement between CNT and direct rate determination is significantly lower than what is expected for the bulk system.

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“…They can then grow (or shrink) by exchanging monomers with other particles, as well as through collision and occasional collision and coalescence events (41). When supersaturation is increased until the free-energy barrier is comparable with k B T, the solution undergoes spinodal decomposition (42,43), at which point the particles are generated in such large numbers that growth by direct collision and coalescence with other particles can dominate (Fig. 4D).…”

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confidence: 99%

Crystallization by particle attachment in synthetic, biogenic, and geologic environments

Yoreo

Gilbert

Sommerdijk

et al. 2015

Science

1,614

1,637

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Field and laboratory observations show that crystals commonly form by the addition and attachment of particles that range from multi-ion complexes to fully formed nanoparticles. The particles involved in these nonclassical pathways to crystallization are diverse, in contrast to classical models that consider only the addition of monomeric chemical species. We review progress toward understanding crystal growth by particle-attachment processes and show that multiple pathways result from the interplay of free-energy landscapes and reaction dynamics. Much remains unknown about the fundamental aspects, particularly the relationships between solution structure, interfacial forces, and particle motion. Developing a predictive description that connects molecular details to ensemble behavior will require revisiting long-standing interpretations of crystal formation in synthetic systems, biominerals, and patterns of mineralization in natural environments.

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Heterogeneous nucleation in the low-barrier regime

Cited by 18 publications

References 50 publications

Diffusion in quasi-one-dimensional channels: A small system n, p, T, transition state theory for hopping times

Diffusion in quasi-one-dimensional channels: A small system n, p, T, transition state theory for hopping times

Crystallization of Lennard-Jones nanodroplets: From near melting to deeply supercooled

Crystallization by particle attachment in synthetic, biogenic, and geologic environments

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