Extended study of molecular dynamics simulation of homogeneous vapor-liquid nucleation of water

Matsubara, Hiroki; Kondo, Takahiro; Ebisuzaki, Toshikazu; Yasuoka, Kenji

doi:10.1063/1.2803899

Cited by 50 publications

(92 citation statements)

References 46 publications

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“…Furthermore, we arrive at the same nucleation rate over a wide range of threshold sizes, as seen in earlier nucleation simulations. 57 For the linear fits, the initial lag time must be ignored. This simply reflects the time needed for the quasi-steady state gas to fully form (finally resulting in the distribution of subcritical clusters), and also for stable clusters to grow to a certain size.…”

Section: Discussionmentioning

confidence: 99%

Large scale molecular dynamics simulations of homogeneous nucleation

Diemand

Angélil

Tanaka

et al. 2013

The Journal of Chemical Physics

118

163

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We present results from large-scale molecular dynamics (MD) simulations of homogeneous vapor-to-liquid nucleation. The simulations contain between 1 × 109 and 8 × 109 Lennard-Jones (LJ) atoms, covering up to 1.2 s (56 × 106 time-steps). They cover a wide range of supersaturation ratios, S = 1.55-104, and temperatures from kT = 0.3 to 1.0 (where is the depth of the LJ potential, and k is the Boltzmann constant). We have resolved nucleation rates as low as 1017 cm-3 s-1 (in the argon system), and critical cluster sizes as large as 100 atoms. Recent argon nucleation experiments probe nucleation rates in an overlapping range, making the first direct comparison between laboratory experiments and molecular dynamics simulations possible: We find very good agreement within the uncertainties, which are mainly due to the extrapolations of argon and LJ saturation curves to very low temperatures. The self-consistent, modified classical nucleation model of Girshick and Chiu [J. Chem. Phys. 93, 1273 (1990)] underestimates the nucleation rates by up to 9 orders of magnitudes at low temperatures, and at kT = 1.0 it overestimates them by up to 105. The predictions from a semi-phenomenological model by Laaksonen et al. [Phys. Rev. E 49, 5517 (1994)] are much closer to our MD results, but still differ by factors of up to 104 in some cases. At low temperatures, the classical theory predicts critical clusters sizes, which match the simulation results (using the first nucleation theorem) quite well, while the semi-phenomenological model slightly underestimates them. At kT = 1.0 , the critical sizes from both models are clearly too small. In our simulations the growth rates per encounter, which are often taken to be unity in nucleation models, lie in a range from 0.05 to 0.24. We devise a new, empirical nucleation model based on free energy functions derived from subcritical cluster abundances, and find that it performs well in estimating nucleation rates. We present results from large-scale molecular dynamics (MD) simulations of homogeneous vapor-toliquid nucleation. The simulations contain between 1 × 10 9 and 8 × 10 9 Lennard-Jones (LJ) atoms, covering up to 1.2 μs (56 × 10 6 time-steps). They cover a wide range of supersaturation ratios, S 1.55-10 4 , and temperatures from kT = 0.3 to 1.0 (where is the depth of the LJ potential, and k is the Boltzmann constant). We have resolved nucleation rates as low as 10 17 cm −3 s −1 (in the argon system), and critical cluster sizes as large as 100 atoms. Recent argon nucleation experiments probe nucleation rates in an overlapping range, making the first direct comparison between laboratory experiments and molecular dynamics simulations possible: We find very good agreement within the uncertainties, which are mainly due to the extrapolations of argon and LJ saturation curves to very low temperatures. The self-consistent, modified classical nucleation model of Girshick and Chiu [J. Chem. Phys. 93, 1273 (1990)] underestimates the nucleation rates by up to 9 orders of magnitudes at l...

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Section: Discussionmentioning

confidence: 99%

Large scale molecular dynamics simulations of homogeneous nucleation

Diemand

Angélil

Tanaka

et al. 2013

The Journal of Chemical Physics

118

163

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“…This article is structured as follows: In Section II, a review is made of the available routes to the Tolman length and the surface tension by molecular simulation. MD simulation methods immediately related to nucleation itself, from which information of the excess free energy of curved interfaces can also be deduced [26][27][28][29], are not included in that discussion; in this regard, the reader is referred to Chkonia et al [30]. Section III is dedicated to a brief outline of how Tolman's thermodynamic approach can be transformed by analysing the surface tension in terms of η and ϕ rather than δ and 1/R γ .…”

Section: Introductionmentioning

confidence: 99%

Excess equimolar radius of liquid drops

et al. 2012

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The curvature dependence of the surface tension is related to the excess equimolar radius of liquid drops, i.e., the deviation of the equimolar radius from that defined with the macroscopic capillarity approximation. Based on the Tolman [J. Chem. Phys. 17, 333 (1949)] approach and its interpretation by Nijmeijer et al. [J. Chem. Phys. 96, 565 (1991)], the surface tension of spherical interfaces is analysed in terms of the pressure difference due to curvature. In the present study, the excess equimolar radius, which can be obtained directly from the density profile, is used instead of the Tolman length. Liquid drops of the truncated-shifted Lennard-Jones fluid are investigated by molecular dynamics simulation in the canonical ensemble, with equimolar radii ranging from 4 to 33 times the Lennard-Jones size parameter σ. In these simulations, the magnitudes of the excess equimolar radius and the Tolman length are shown to be smaller than σ/2. Other methodical approaches, from which mutually contradicting findings have been reported, are critically discussed, outlining possible sources of inaccuracy.

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“…As a consequence, the past decade has witnessed a surge of contributions devoted to improving the understanding of the process time scales, with many studies focusing on the large scale calculation of nucleation rates by means of molecular dynamics ͑MD͒, [1][2][3][4] on the benchmark of currently available theories ͑e.g., classical nucleation theory, extended liquid drop modeldynamical nucleation theory, and other semiphenomenological models͒, 1,2,5 and on the calculation of the work necessary to build a cluster from the supersaturated vapor. 6,7 Despite these efforts, the routine application of computational approaches to the calculation of nucleation rates for experimentally relevant systems still appears as a distant goal, the exception being perhaps the prediction of the critical cluster size that can be done by means of thermodynamic integration.…”

Section: Introductionmentioning

confidence: 99%

On possible simplifications in the theoretical description of gas phase atomic cluster dissociation

Mella¹

2009

The Journal of Chemical Physics

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In this work, we investigate the possibility of describing gas phase atomic cluster dissociation by means of variational transition state theory ͑vTST͒ in the microcanonical ensemble. A particular emphasis is placed on benchmarking the accuracy of vTST in predicting the dissociation rate and kinetic energy release of a fragmentation event as a function of the cluster size and internal energy. The results for three Lennard-Jones clusters ͑LJ n , n =8,14,19͒ indicate that variational transition state theory is capable of providing results of accuracy comparable to molecular dynamics simulations at a reduced computational cost. Possible simplifications of the master equation formalism used to model a dissociation cascade are also suggested starting from molecular dynamics results. In particular, it is found that the dissociation rate is only weakly dependent on the cluster total angular momentum J for the three cluster sizes considered. This would allow one to partially neglect the J-dependency of the kinetic coefficients, leading to a substantial decrease in the computational effort needed for the complete description of the cascade process. The impact of this investigation on the modeling of the nucleation process is discussed.

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Extended study of molecular dynamics simulation of homogeneous vapor-liquid nucleation of water

Cited by 50 publications

References 46 publications

Large scale molecular dynamics simulations of homogeneous nucleation

Large scale molecular dynamics simulations of homogeneous nucleation

Excess equimolar radius of liquid drops

On possible simplifications in the theoretical description of gas phase atomic cluster dissociation

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