Theory and Monte Carlo simulation of physical clusters in the imperfect vapor

Lee, Jong K.; Barker, John A.; Abraham, Farid F.

doi:10.1063/1.1679638

Cited by 421 publications

(121 citation statements)

References 15 publications

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“…In the present work, we set R ) 5. Lee et al 65 noted that the Helmholtz free energy for small Lennard-Jones argon clusters is relatively insensitive to the simulation radius, r sim , for R ≈ 5. Some studies of the dependence on R were made for small water cluster free energy differences 66 and for a few small (km, m) clusters.…”

Section: Cluster Free Energy Differencesmentioning

confidence: 99%

Monte Carlo Simulations of Small Sulfuric Acid−Water Clusters

Kathmann

Hale

2001

J. Phys. Chem. B

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Effective atom-atom potentials are developed for binary sulfuric acid-water clusters and applied in a Bennett Metropolis Monte Carlo calculation to determine free energy differences for small neighboring sized clusters of fixed composition at 298 K. The atom-atom pair potentials consist of Lennard-Jones short-range and Coulombic long-range terms and assume rigid SO 4 2δ-with two unconstrained H δ+ and rigid H 2 O molecules interacting via revised central force (RSL2) potentials. The potential parameters are determined from both ab initio studies and tests of the potential using the statistical mechanical formalism for binary cluster size distributions. In the potential tests, fixed composition free energy differences, δf km,m , for [H 2 O] km [H 2 SO 4 ] m clusters are plotted versus (km + m) -1/3 , and the resulting slope and intercept (in the large cluster regime) are used to extract model dependent binary liquid surface tension and partial vapor pressures at 298 K. The potential parameters are adjusted to obtain approximate agreement with experimental surface tension and partial vapor pressures for k ) 1 and 4 (84% and 57% weight percent H 2 SO 4 , respectively). The free energy differences for m e 15 are presented, together with internal cluster energy contributions, snapshots of cluster structure, and evidence for onset of the large cluster regime near m ) 5. The long-range goals have been to test the free energy difference procedure for studying binary cluster properties and to develop model potentials appropriate for the simulation of small binary clusters at low temperatures characteristic of stratospheric sulfuric acid-water aerosols.

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Section: Cluster Free Energy Differencesmentioning

confidence: 99%

Monte Carlo Simulations of Small Sulfuric Acid−Water Clusters

Kathmann

Hale

2001

J. Phys. Chem. B

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“…It may be shown that (6) which shifts attention to the free energy difference F (j)− F (j − 1) associated with the addition of a molecule to a (j − 1)-cluster. Computing these differences is the basis of an approach has been used extensively in calculations of cluster free energies [17][18][19][20][21][22][23]. But nucleation is actually controlled by the properties of clusters near the critical size, and one drawback of computing the differences F (j)−F (j −1) is that the predicted nucleation rate could be susceptible to the accumulation of errors in evaluating such a sequence.…”

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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“…3,7,8 It succeeds in capturing the qualitative behavior, but fails to predict the correct temperature dependency of nucleation rates, and the predicted rates are often orders of magnitude different from measurements in unary and in multicomponent systems. [9][10][11][12] Molecular dynamics and Monte Carlo simulations are important sources of information on nucleation, [13][14][15][16][17][18][19] that for complicated mixtures and realistic conditions comes at the expense of large computational costs. 20 a) Electronic mail: oivind.wilhelmsen@ntnu.no…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic stability of nanosized multicomponent bubbles/droplets: The square gradient theory and the capillary approach

Wilhelmsen

Bedeaux

Kjelstrup

et al. 2014

The Journal of Chemical Physics

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Formation of nanosized droplets/bubbles from a metastable bulk phase is connected to many unresolved scientific questions. We analyze the properties and stability of multicomponent droplets and bubbles in the canonical ensemble, and compare with single-component systems. The bubbles/droplets are described on the mesoscopic level by square gradient theory. Furthermore, we compare the results to a capillary model which gives a macroscopic description. Remarkably, the solutions of the square gradient model, representing bubbles and droplets, are accurately reproduced by the capillary model except in the vicinity of the spinodals. The solutions of the square gradient model form closed loops, which shows the inherent symmetry and connected nature of bubbles and droplets. A thermodynamic stability analysis is carried out, where the second variation of the square gradient description is compared to the eigenvalues of the Hessian matrix in the capillary description. The analysis shows that it is impossible to stabilize arbitrarily small bubbles or droplets in closed systems and gives insight into metastable regions close to the minimum bubble/droplet radii. Despite the large difference in complexity, the square gradient and the capillary model predict the same finite threshold sizes and very similar stability limits for bubbles and droplets, both for single-component and two-component systems. © 2014 AIP Publishing LLC. [http://dx

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Theory and Monte Carlo simulation of physical clusters in the imperfect vapor

Cited by 421 publications

References 15 publications

Monte Carlo Simulations of Small Sulfuric Acid−Water Clusters

Monte Carlo Simulations of Small Sulfuric Acid−Water Clusters

Free energies of molecular clusters determined by guided mechanical disassembly

Thermodynamic stability of nanosized multicomponent bubbles/droplets: The square gradient theory and the capillary approach

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