Forward-flux sampling with jumpy order parameters

Haji-Akbari, Amir

doi:10.1063/1.5018303

Cited by 54 publications

(91 citation statements)

References 67 publications

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“…Since brute force results contain no approximation, and they can be regarded as a benchmark for methodologies aiming to estimate J for nucleation, these results support the validity of CNT in describing the nucleation behaviour of colloidal electrolytes (at least at T* = 1). The discrepancy between the Seeding and FFS nucleation rates is somewhat not surprising since, on the one hand, it has been previously found that FFS calculations may underestimate the nucleation rate by a few orders of magnitude when the sampling is not extremely large, 26,44,114,115 and on the other, because Seeding results may also have an uncertainty (systematic + statistical) of about 3-5 orders of magnitude in the nucleation rate (see Fig. 5).…”

Section: B Crystal Nucleation Rate Of the Different Polymorphsmentioning

confidence: 85%

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

et al. 2021

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Section: B Crystal Nucleation Rate Of the Different Polymorphsmentioning

confidence: 85%

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

et al. 2021

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“…5, and we will discuss it below. Besides, there is a recent paper 30 which reveals that although FFS is not sensitive to order parameter, the conventional FFS sometimes still underestimates the nucleation rate by several orders of magnitude.…”

Section: Discussionmentioning

confidence: 99%

Calculation of critical nucleation rates by the persistent embryo method: application to quasi hard sphere models

et al. 2018

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We study crystal nucleation of the Weeks-Chandler-Andersen (WCA) model, using the recently introduced Persistent Embryo Method (PEM). The method provides detailed characterization of pre-critical, critical and post-critical nuclei, as well as nucleation rates that compare favorably with those obtained using other methods (umbrella sampling, forward flux sampling or seeding). We further map our results to a hard sphere model allowing to compare with other existing predictions. Implications for experiments are also discussed.* Email: yangsun@ameslab.gov (Y.S.) or fzhang@ameslab.gov (F.Z.) 11 . Experimental nucleation rates, however, remain in significant disagreement with most existing theoretical predictions using these simple models 4,12 .Recently, we have introduced the Persistent Embryo Method (PEM) 13 and applied it to the investigation of the nucleation of pure Ni and binary CuZr by all atom MD simulations. In this paper, we demonstrate that PEM is an efficient method by applying it to the Weeks-Chandler-Andersen (WCA) model 14 , assuming the validity of CNT. As we describe further below, PEM can measure the nucleation rate in the low-density regime and does not make any geometrical assumption on the shape of nucleus. Moreover, PEM can obtain the unbiased configuration of the critical nucleus. We expect that PEM will become the method of choice as the optimal implementation of CNT for certain problems. Furthermore, given the current disagreements between nucleation rates as measured in experiments or calculated by theory, new techniques are crucial, in that they provide additional insights on the origins of such discrepancies. This paper is organized as follows: in Sec. 2 we present the WCA model, including the description of Brownian dynamics and order parameter. In Sec. 3 we show the method and discuss the calculation of other necessary quantities, such as the chemical potential. Sec. 4 describes the persistent-embryo method (PEM) and Sec. 5 describes the determination of attachment rate. In Sec. 6, we derive the rate equation and present our predictions. In Sec. 7, we discuss our results and compare them with existing estimates obtained by other methods. A comparison with experimental results is also included. The conclusions are left for Sec. 8. WCA model and simulation details

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“…Note that the low saving frequency might lead to large jumps in the order parameter from one frame to the next. The effect of such jumpiness has been studied in the context of FFS in ref ( 64 ).…”

Section: Methodsmentioning

confidence: 99%

Rate Prediction for Homogeneous Nucleation of Methane Hydrate at Moderate Supersaturation Using Transition Interface Sampling

Arjun

Bolhuis

2020

J. Phys. Chem. B

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The crystallization of methane hydrates via homogeneous nucleation under natural, moderate conditions is of both industrial and scientific relevance, yet still poorly understood. Predicting the nucleation rates at such conditions is notoriously difficult due to high nucleation barriers, and requires, besides an accurate molecular model, enhanced sampling. Here, we apply the transition interface sampling technique, which efficiently computes the exact rate of nucleation by generating ensembles of unbiased dynamical trajectories crossing predefined interfaces located between the stable states. Using an accurate atomistic force field and focusing on specific conditions of 280 K and 500 bar, we compute for nucleation directly into the sI crystal phase at a rate of ∼10 –17 nuclei per nanosecond per simulation volume or ∼10 2 nuclei per second per cm 3 , in agreement with consensus estimates for nearby conditions. As this is most likely fortuitous, we discuss the causes of the large differences between our results and previous simulation studies. Our work shows that it is now possible to compute rates for methane hydrates at moderate supersaturation, without relying on any assumptions other than the force field.

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Forward-flux sampling with jumpy order parameters

Cited by 54 publications

References 67 publications

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

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

Calculation of critical nucleation rates by the persistent embryo method: application to quasi hard sphere models

Rate Prediction for Homogeneous Nucleation of Methane Hydrate at Moderate Supersaturation Using Transition Interface Sampling

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