Molecular dynamics of homogeneous nucleation in the vapor phase of Lennard-Jones. III. Effect of carrier gas pressure

Yasuoka, Kenji; Zeng, Xiao Cheng

doi:10.1063/1.2712436

Cited by 32 publications

(11 citation statements)

References 21 publications

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“…35 Nucleation rate analyses using MD simulations have actually been well documented for monatomic systems forming droplets or bubbles through homogeneous and heterogeneous nucleation. [36][37][38][39][40][41][42][43][44][45] This study is initiated from the assumption that the various methods to analyze the nucleation rate and critical nucleus size may be applicable for other nucleation processes, and therefore we have used these methods to analyze hydrate nucleation. [46][47][48][49] In this study, we analyzed the simulation results from Barnes et al 35 and calculated the nucleation rate and critical nucleus size of the methane hydrates by implementing methods originally applied to analyze vapor-to-liquid nucleation.…”

Section: Introductionmentioning

confidence: 99%

Nucleation rate analysis of methane hydrate from molecular dynamics simulations

et al. 2015

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Clathrate hydrates are solid crystalline structures most commonly formed from solutions that have nucleated to form a mixed solid composed of water and gas. Understanding the mechanism of clathrate hydrate nucleation is essential to grasp the fundamental chemistry of these complex structures and their applications. Molecular dynamics (MD) simulation is an ideal method to study nucleation at the molecular level because the size of the critical nucleus and formation rate occur on the nano scale. Various analysis methods for nucleation have been developed through MD to analyze nucleation. In particular, the mean first-passage time (MFPT) and survival probability (SP) methods have proven to be effective in procuring the nucleation rate and critical nucleus size for monatomic systems. This study assesses the MFPT and SP methods, previously used for monatomic systems, when applied to analyzing clathrate hydrate nucleation. Because clathrate hydrate nucleation is relatively difficult to observe in MD simulations (due to its high free energy barrier), these methods have yet to be applied to clathrate hydrate systems. In this study, we have analyzed the nucleation rate and critical nucleus size of methane hydrate using MFPT and SP methods from data generated by MD simulations at 255 K and 50 MPa. MFPT was modified for clathrate hydrate from the original version by adding the maximum likelihood estimate and growth effect term. The nucleation rates calculated by MFPT and SP methods are within 5%, and the critical nucleus size estimated by the MFPT method was 50% higher, than values obtained through other more rigorous but computationally expensive estimates. These methods can also be extended to the analysis of other clathrate hydrates.

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Section: Introductionmentioning

confidence: 99%

Nucleation rate analysis of methane hydrate from molecular dynamics simulations

et al. 2015

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“…The nucleation of a new phase is challenging in experiments due to the insufficient temporal and spatial experimental resolutions. Instead, density functional theory and computer simulation [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] have also been extensively used in this eld. In this work, we studied the vapor-to-liquid nucleation of microdroplets and their subsequent growth on nano-pillared substrates, using a constrained lattice density functional theory (constrained LDFT).…”

Section: Introductionmentioning

confidence: 99%

Condensation of droplets on nanopillared hydrophobic substrates

et al. 2014

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Using the constrained lattice density functional theory, we investigated the mechanism of droplet condensation, including droplet nucleation and growth, on nanopillared substrates. We find that similar to a macroscopic droplet on such a substrate, the critical nucleus also exhibits either the Wenzel or Cassie wetting state, depending on both the pillar height and the interpillar spacing. Our calculations show that there exists a critical value of the interpillar spacing, above which the critical nucleus is always in the Wenzel state and the pillared substrate always promotes the nucleation as compared to the smooth substrate, regardless of the pillar height. Below the critical interpillar spacing, however, the pillars always inhibit the nucleation, and the wetting state of the critical nucleus depends on the pillar height. Furthermore, our results demonstrate that the wetting state of the critical nuclei is not necessarily the wetting state of the formed microdroplets: droplets originated from the critical nuclei in the Wenzel state may change into the Cassie state spontaneously during the droplet growth process if the pillar height is greater than a critical value.

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“…Several publications have dealt at least partly with this question but none could in our view undoubtedly answer it. [27][28][29][30][31] Moreover, the influence of temperature fluctuations and nonisothermal effects on the nucleation rate has long been discussed theoretically in the literature but, in our knowledge, never tested in a molecular simulation.…”

Section: Introductionmentioning

confidence: 99%

Influence of thermostats and carrier gas on simulations of nucleation

Wedekind¹,

Reguera²,

Strey³

2007

The Journal of Chemical Physics

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We investigate the influence of carrier gas and thermostat on molecular dynamics (MD) simulations of nucleation. The task of keeping the temperature constant in MD simulations is not trivial and an inefficient thermalization may have a strong influence on the results. Different thermostating mechanisms have been proposed and used in the past. In particular, we analyze the efficiency of velocity rescaling, Nose-Hoover, and a carrier gas (mimicking the experimental situation) by extensive MD simulations. Since nucleation is highly sensitive to temperature, one would expect that small variations in temperature might lead to differences in nucleation rates of up to several orders of magnitude. Surprisingly, the results indicate that the choice of the thermostating method in a simulation does not have--at least in the case of Lennard-Jones argon--a very significant influence on the nucleation rate. These findings are interpreted in the context of the classical theory of Feder et al. [Adv. Phys. 15, 111 (1966)] by analyzing the temperature distribution of the nucleating clusters. We find that the distribution of cluster temperatures is non-Gaussian and that subcritically sized clusters are colder while postcritically sized clusters are warmer than the bath temperature. However, the average temperature of all clusters is found to be always higher than the bath temperature.

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Molecular dynamics of homogeneous nucleation in the vapor phase of Lennard-Jones. III. Effect of carrier gas pressure

Cited by 32 publications

References 21 publications

Nucleation rate analysis of methane hydrate from molecular dynamics simulations

Nucleation rate analysis of methane hydrate from molecular dynamics simulations

Condensation of droplets on nanopillared hydrophobic substrates

Influence of thermostats and carrier gas on simulations of nucleation

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