Driving Ordering Processes in Molecular-Dynamics Simulations

Dittmar, Harro; Kusalik, Peter G.

doi:10.1103/physrevlett.112.195701

Cited by 6 publications

(7 citation statements)

References 37 publications

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“…We investigated the growth velocity of a flat interface, but presumably the same approach can be used for studying other reaction paths. As an example, by setting up a system with a crystallite [30][31][32], it should be possible to compute the growth velocity of a curved solid-liquid interface. We leave such studies for future investigations.…”

Section: An Alternative To Forward Flux Samplingmentioning

confidence: 99%

Computing the crystal growth rate by the interface pinning method

Pedersen

Hummel

Dellago

2015

The Journal of Chemical Physics

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An essential parameter for crystal growth is the kinetic coefficient given by the proportionality between supercooling and average growth velocity. Here, we show that this coefficient can be computed in a single equilibrium simulation using the interface pinning method where two-phase configurations are stabilized by adding a spring-like bias field coupling to an order-parameter that discriminates between the two phases. Crystal growth is a Smoluchowski process and the crystal growth rate can, therefore, be computed from the terminal exponential relaxation of the order parameter. The approach is investigated in detail for the Lennard-Jones model. We find that the kinetic coefficient scales as the inverse square-root of temperature along the high temperature part of the melting line. The practical usability of the method is demonstrated by computing the kinetic coefficient of the elements Na and Si from first principles. A generalized version of the method may be used for computing the rates of crystal nucleation or other rare events. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [http://dx

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Section: An Alternative To Forward Flux Samplingmentioning

confidence: 99%

Computing the crystal growth rate by the interface pinning method

Pedersen

Hummel

Dellago

2015

The Journal of Chemical Physics

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“…Recently all-atom simulations of homogeneous ice nucleation have been performed 89 with the help of the forward-flux sampling technique 90,91 . The latter seems like a promising approach for nucleation simulations 35,71,76,89,[92][93][94] although there are of course many other free energy and enhanced sampling techniques 70,[95][96][97][98][99][100][101][102] that could be used. Improvement in the water-surface interaction potential is of equal importance if one wishes to investigate heterogeneous ice nucleation.…”

Section: Future Perspective and Experimental Verificationmentioning

confidence: 99%

The Many Faces of Heterogeneous Ice Nucleation: Interplay Between Surface Morphology and Hydrophobicity

et al. 2015

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What makes a material a good ice nucleating agent? Despite the importance of heterogeneous ice nucleation to a variety of fields, from cloud science to microbiology, major gaps in our understanding of this ubiquitous process still prevent us from answering this question. In this work, we have examined the ability of generic crystalline substrates to promote ice nucleation as a function of the hydrophobicity and the morphology of the surface. Nucleation rates have been obtained by brute-force molecular dynamics simulations of coarse-grained water on top of different surfaces of a model fcc crystal, varying the watersurface interaction and the surface lattice parameter. It turns out that the lattice mismatch of the surface with respect to ice, customarily regarded as the most important requirement for a good ice nucleating agent, is at most desirable but not a requirement. On the other hand, the balance between the morphology of the surface and its hydrophobicity can significantly alter the ice nucleation rate and can also lead to the formation of up to three different faces of ice on the same substrate. We have pinpointed three circumstances where heterogeneous ice nucleation can be promoted by the crystalline surface: i) the formation of a water overlayer that acts as an in-plane template; ii) the emergence of a contact layer buckled in an ice-like manner; and iii) nucleation on compact surfaces with very high interaction strength. We hope that this extensive systematic study will foster future experimental work aimed at testing the physiochemical understanding presented herein.

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“…Future studies should aim to continue improving simulation methodologies to overcome these limitations (e.g. by adapting a driven energy conversion approach to accelerate the nucleation rates independent of a structural bias) [131,132]. The continued improvement of molecular force fields and inclusion of nuclear quantum effects [133,134], along with advancements to data analysis and visualization methods, will also further enhance attempts to realize complete, realistic molecular-level pictures of crystallization, and improve our understanding of their roles in various physical, chemical and biological processes [135][136][137][138].…”

Section: Discussionmentioning

confidence: 99%

Characterizing key features in the formation of ice and gas hydrate systems

Liang

Hall

Laaksonen

et al. 2019

Phil. Trans. R. Soc. A.

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Crystallization in liquids is critical to a range of important processes occurring in physics, chemistry and life sciences. In this article, we review our efforts towards understanding the crystallization mechanisms, where we focus on theoretical modelling and molecular simulations applied to ice and gas hydrate systems. We discuss the order parameters used to characterize molecular ordering processes and how different order parameters offer different perspectives of the underlying mechanisms of crystallization. With extensive simulations of water and gas hydrate systems, we have revealed unexpected defective structures and demonstrated their important roles in crystallization processes. Nucleation of gas hydrates can in most cases be characterized to take place in a two-step mechanism where the nucleation occurs via intermediate metastable precursors, which gradually reorganizes to a stable crystalline phase. We have examined the potential energy landscapes explored by systems during nucleation, and have shown that these landscapes are rugged and funnel-shaped. These insights provide a new framework for understanding nucleation phenomena that has not been addressed in classical nucleation theory. This article is part of the theme issue ‘The physics and chemistry of ice: scaffolding across scales, from the viability of life to the formation of planets’.

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Driving Ordering Processes in Molecular-Dynamics Simulations

Cited by 6 publications

References 37 publications

Computing the crystal growth rate by the interface pinning method

Computing the crystal growth rate by the interface pinning method

The Many Faces of Heterogeneous Ice Nucleation: Interplay Between Surface Morphology and Hydrophobicity

Characterizing key features in the formation of ice and gas hydrate systems

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