Molecular dynamics of the surface tension of a drop

In view of the continued disputes on the fundamental question of whether the surface tension of a vapour bubble in liquid argon increases, or decreases, or remains unchanged with the increase of curvature radius, a cylindrical vapour bubble of argon is studied by molecular dynamics simulation in this paper instead of spherical vapour bubble so as to reduce the statistical error. So far, the surface tension of the cylindrical vapour bubble has not been studied by molecular dynamics simulation in the literature. Our results show that the surface tension decreases with radius increasing. By fitting the Tolman equation with our data, the Tolman length δ = −0.6225 sigma is given under cut-off radius 2.5σ, where σ = 0.3405 nm is the diameter of an argon atom. The Tolman length of Ar being negative is affirmed and the Tolman length of Ar being approximately zero given in the literature is negated, and it is pointed out that this error is attributed to the application of the inapplicable empirical equation of state and the neglect of the difference between surface tension and an equimolar surface.

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“…(6) gives the same result for any pair of R l and R v in the bulk phase. Besides, Laplace equation [12] …”

Section: Some Equations For Cylindrical Vapour Bubblesmentioning

confidence: 99%

“…For cylindrical vapour bubbles, the Tolman equation (3) should be replaced by Tolman equation [12] γ…”

Section: Theoretical Basis and Calculation Schemementioning

confidence: 99%

Size-dependent surface tension of a cylindrical nanobubble in liquid Ar

2012

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“…Such an approach has been attempted before, 12,13 with limited success due to the difficulty of the calculation and the limited computational resources available at the time. Instead, Eq.…”

Section: Introductionmentioning

confidence: 99%

“…͑6͒ below, [9][10][11] or were inconclusive. 12, 13 Moody and Attard 14 determined the Tolman length from simulations of a liquid near coexistence solvating a hard-wall cavity and found that the Tolman length was positive at low temperatures, changed sign at a certain temperature, and became increasingly negative as the temperature increased. It is not clear how the Tolman length for a solvated hard-wall cavity in a liquid near coexistence compares with that of a liquid drop surrounded by its vapor, though these authors give reasons why they ought to be the similar.…”

Section: Introductionmentioning

confidence: 99%

“…͑4͒ has been used to derive the so-called "virial" expressions for both the surface tension of a planar interface and for the Tolman length. 12 , and z 2 = z 1 + sr, and it is understood that the integration over z runs from the liquid to the vapor phase and where the z = 0 plane is chosen to coincide with the equimolar surface. The determination of the Tolman length in molecular dynamics ͑MD͒ simulations via Eq.…”

Section: Introductionmentioning

confidence: 99%

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Direct determination of the Tolman length from the bulk pressures of liquid drops via molecular dynamics simulations

Giessen

Blokhuis

2009

The Journal of Chemical Physics

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An expression for the difference in pressure between a liquid drop in equilibrium with its vapor ⌬p = p ᐉ − p v is derived from previous expressions for the components of the Irving-Kirkwood pressure tensor. This expression, as well as the bulk values of the pressure tensor, is then evaluated via molecular dynamics simulations of particles interacting through a truncated Lennard-Jones potential. We determine the Tolman length ␦ from the dependence of ⌬p on the equimolar radius. We determine the Tolman length to be ␦ = −0.10Ϯ 0.02 in units of the particle diameter. This is the first determination of the Tolman length for liquid droplets via the pressure tensor route through computer simulation that is negative, in contrast to all previous results from simulation, but in agreement with results from density functional theory. In addition, we study the planar liquid-vapor interface and observe a dependence of the physical properties of the system on the system size, as measured by the surface area.

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Mesoscopic Simulation of Aggregates in Surfactant/Oil/Water Systems

Yuan

Cai

2003

Chin. J. Chem.

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The aggregates in sodium dedecylsufphate (SDS)/dimethylbe& water system have been investigated using dissipative @des dynamic (DPD) simulation method. Thrwgh analyzing threedimen-One is the phase separabion, which is clearly observed by water density and the aggregates in the simulated cell; another is the water morphology it~ reverse rnide, which can be found through the isodensity slice of water including bound water, trapped water and bulky water; the third is about the water/oil interface, i . c. , ionic surfadant molecules, SDS , prefer to exist in the interface between water and oil p k e at the low concentration.$anal structures of aggregates, three sinsllated d t s are found.

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Molecular dynamics of the surface tension of a drop

Cited by 160 publications

References 21 publications

Size-dependent surface tension of a cylindrical nanobubble in liquid Ar

Size-dependent surface tension of a cylindrical nanobubble in liquid Ar

Direct determination of the Tolman length from the bulk pressures of liquid drops via molecular dynamics simulations

Mesoscopic Simulation of Aggregates in Surfactant/Oil/Water Systems

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