Semiphenomenological theory of homogeneous vapor–liquid nucleation

Kalikmanov, V. I.; Dongen, M. E. H. van

doi:10.1063/1.470662

Cited by 51 publications

(39 citation statements)

References 29 publications

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“…It represents a thermodynamic barrier, with a maximum at the critical size, that limits the natural tendency for small molecular clusters to grow into large droplets when exposed to a supersaturated vapour. CNT has been modified in several ways, for example by introducing a size-dependent surface tension [14] or by introducing compatibility with nonideal vapour properties [15,16].…”

Section: Introductionmentioning

confidence: 99%

Free energies of molecular clusters determined by guided mechanical disassembly

Tang

Ford

2015

Phys. Rev. E

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The excess free energy of a molecular cluster is a key quantity in models of the nucleation of droplets from a metastable vapour phase; it is often viewed as the free energy arising from the presence of an interface between the two phases. We show how this quantity can be extracted from simulations of the mechanical disassembly of a cluster using guide particles in molecular dynamics. We disassemble clusters ranging in size from 5 to 27 argon-like Lennard-Jones atoms, thermalised at 60 K, and obtain excess free energies, by means of the Jarzynski equality, that are consistent with previous studies. We only simulate the cluster of interest, in contrast to approaches that require a series of comparisons to be made between clusters differing in size by one molecule. We discuss the advantages and disadvantages of the scheme and how it might be applied to more complex systems.

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Section: Introductionmentioning

confidence: 99%

Free energies of molecular clusters determined by guided mechanical disassembly

Tang

Ford

2015

Phys. Rev. E

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“…Density functional theory (DFT) 35 and the extended modified liquid drop model take into account the extended transition rea) Electronic mail: diemand@physik.uzh.ch; URL: http://www.physik.uzh.ch/~diemand/ gion from liquid to vapor, sometimes referred to as the the "corona," and match MD results far better than the CNT. Here we use MD simulations to test another approach: the semiphenomenological (SP) model, [36][37][38][39] which corrects the cluster formation energy from CNT by using the second virial coefficient. The SP model agrees well with experimental data on water, nonane and n-alcohols, 37 and also with MD simulations of Lennard-Jones atoms at high supersaturations.…”

Section: Introductionmentioning

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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“…3, theoretical curves for the temperatures of interest are included for the semiphenomenological theory of Kalikmanov and Van Dongen. 3 It finds its basis in the Fisher model for the cluster distribution and a radius-dependent Tolman-like form for the microscopic surface tension. The characteristic Tolman length is found by matching the equilibrium cluster distribution to ͑empirical͒ saturation pressure data.…”

Section: Resultsmentioning

confidence: 99%

“…Several routes to describe the formation of critical nuclei out of a vapor consisting of a distribution of ͑subcritical͒ clusters have been developed until now. 2,3 Comparison of the experimentally determined nucleation rates to these models still meets considerable problems, since severe discrepancies exist between data sets obtained by different experimental groups. These are first of all caused by the use of different substances for nucleation studies.…”

Section: Introductionmentioning

confidence: 99%

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Homogeneous nucleation rates for n-pentanol from expansion wave tube experiments

Luijten

Baas

Dongen

1997

The Journal of Chemical Physics

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Within the scope of joint experiments by the international Nucleation Workshop Group, nucleation experiments on n-pentanol were carried out using a pulse-expansion wave tube. Data were obtained for nucleation at temperatures between 240 K and 260 K. Total pressures of the carrier gas ͑helium͒ during nucleation varied from 89 to 109 kPa. The results are presented in tabular form, to facilitate future comparison. Our results are consistent with existing data by Hrubý et al. Comparisons are made to the Kinetic Classical Theory ͑KCT͒ as well as to the semiphenomenological theory by Kalikmanov and Van Dongen ͑KvD-SPT͒. Although both theories predict nucleation rates that are apparently too low in the temperature range of interest, the KvD-SPT is approximately two orders of magnitude closer to the experimental results.

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Semiphenomenological theory of homogeneous vapor–liquid nucleation

Cited by 51 publications

References 29 publications

Free energies of molecular clusters determined by guided mechanical disassembly

Free energies of molecular clusters determined by guided mechanical disassembly

Large scale molecular dynamics simulations of homogeneous nucleation

Homogeneous nucleation rates for n-pentanol from expansion wave tube experiments

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