On the structure of a free surface of a Lennard-Jones liquid: A Monte Carlo calculation

Abraham, Farid F.; Schreiber, Donald E.; Barker, John A.

doi:10.1063/1.430685

Cited by 89 publications

(11 citation statements)

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“…y FAr X 10 2 Surface thickness A Run dyne/cm (12), while those by MFT are from (5). Under surface thickness column (a) is the value from equation (19), while column (b) is the 10-90 width (see text).…”

Section: And Mft Results For Truncated Lj Mixturesmentioning

confidence: 99%

The vapour-liquid interface for a Lennard-Jones model of argon-krypton mixtures

1984

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We report a molecular dynamics study of the planar vapour-liquid interface for mixtures of Ar and Kr modelled by truncated Lennard~ones potentials at 115.77 K and at two compositions. The simulations yield the density profiles, surface tension, surface of tension, adsorption, and normal and transverse components of the pressure tensor. Both the Irving-Kirkwood (IK) and Harasima (H) forms of the pressure tensor are calculated. The values of the surface tension calculated by the thermodynamic and mechanical (for both the IK and H pressure tensors) routes are in agreement, but the IK and H pressure tensors yield different values for the surface of tension, as expected. These results are compared with predictions of the mean field theory (MFT) of the interface. The agreement is generally good, the principal differences being due to the fact that the MFT predicts too low a liquid density. The MFT is also used to predict properties of the mixture interface for the full Lennard~Jones potential. For low concentrations of argon, the argon density profile is predicted to be weakly non-monotonic; this effect is larger for the full than for the truncated Lennard~ones potential.

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Section: And Mft Results For Truncated Lj Mixturesmentioning

confidence: 99%

The vapour-liquid interface for a Lennard-Jones model of argon-krypton mixtures

1984

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“…[28][29][30][31] The constraints on computational time meant that the early work was restricted to relatively small systems ͑ca. N = 200-300 particles͒, and as a consequence pronounced finite-size effects were seen.…”

Section: Simulation Of the Interfacial Tensionmentioning

confidence: 99%

Test-area simulation method for the direct determination of the interfacial tension of systems with continuous or discontinuous potentials

Gloor

Jackson

Blas

et al. 2005

The Journal of Chemical Physics

324

367

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A novel test-area ͑TA͒ technique for the direct simulation of the interfacial tension of systems interacting through arbitrary intermolecular potentials is presented in this paper. The most commonly used method invokes the mechanical relation for the interfacial tension in terms of the tangential and normal components of the pressure tensor relative to the interface ͑the relation of Kirkwood and Buff ͓J. Chem. Phys. 17, 338 ͑1949͔͒͒. For particles interacting through discontinuous intermolecular potentials ͑e.g., hard-core fluids͒ this involves the determination of ␦ functions which are impractical to evaluate, particularly in the case of nonspherical molecules. By contrast we employ a thermodynamic route to determine the surface tension from a free-energy perturbation due to a test change in the surface area. There are important distinctions between our test-area approach and the computation of a free-energy difference of two ͑or more͒ systems with different interfacial areas ͑the method of Bennett ͓J. Comput. Phys. 22, 245 ͑1976͔͒͒, which can also be used to determine the surface tension. In order to demonstrate the adequacy of the method, the surface tension computed from test-area Monte Carlo ͑TAMC͒ simulations are compared with the data obtained with other techniques ͑e.g., mechanical and free-energy differences͒ for the vapor-liquid interface of Lennard-Jones and square-well fluids; the latter corresponds to a discontinuous potential which is difficult to treat with standard methods. Our thermodynamic test-area approach offers advantages over existing techniques of computational efficiency, ease of implementation, and generality. The TA method can easily be implemented within either Monte Carlo ͑TAMC͒ or molecular-dynamics ͑TAMD͒ algorithms for different types of interfaces ͑vapor-liquid, liquid-liquid, fluid-solid, etc.͒ of pure systems and mixtures consisting of complex polyatomic molecules.

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“…Abraham and co-workers [26]. For the solid/liquid coexistence, we used a methodà la Hafskjold and Ikeshoji [27].…”

Section: Equilibrium MD Simulation Of Two-phase Systemsmentioning

confidence: 99%

Thermodynamic properties of the 3D Lennard-Jones/spline model

et al. 2019

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In the Lennard-Jones spline (LJ/s) model, the Lennard-Jones (LJ) potential is truncated and splined so that both the pair potential and the force continuously approach zero at rc ≈ 1.74σ. It exhibits the same structural features as the LJ model, but the thermodynamic properties are different due to the shorter range of the potential. One advantage of the model is that simulation times are much shorter. In this work, we present a systematic map of the thermodynamic properties of the LJ/s model from molecular dynamics and Gibbs ensemble Monte Carlo simulations. Accurate results are presented for gas/liquid, liquid/solid and gas/solid coexistence curves, supercritical isotherms up to a reduced temperature of 2 (in LJ units), surface tensions, speed of sound, the Joule-Thomson inversion curve, and the second to fourth virial coefficients. The critical point for the LJ/s model is estimated to be T * c = 0.885 ± 0.002 and P * c = 0.075 ± 0.001, respectively. The triple point is estimated to T * tp = 0.547 ± 0.005 and P * tp = 0.0016 ± 0.0002. Despite the simplicity of the model, the acentric factor was found to be as large as 0.07±0.02. The coexistence densities, saturation pressure, and supercritical isotherms of the LJ/s model were fairly well represented by the Peng-Robison equation of state. We find that Barker-Henderson perturbation theory works much more poorly for the LJ/s model than for the LJ model. The first-order perturbation theory overestimates the critical temperature and pressure by about 10% and 90%, respectively. A second-order perturbation theory that uses the mean compressibility approximation shifts the critical point closer to simulation data, but makes the prediction of the saturation densities worse. It is hypothesized that the reason for this is that the mean compressibility approximation gives a poor representation of the second-order perturbation term for the LJ/s model and that a correction factor is needed at high densities.Our main conclusion is that we at the moment do not have a theory or model that adequately represents the thermodynamic properties of the LJ/s system.

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On the structure of a free surface of a Lennard-Jones liquid: A Monte Carlo calculation

Abstract: Density-functional theory and Monte Carlo simulation for the surface structure and correlation functions of freely jointed Lennard-Jones polymeric fluids

Cited by 89 publications

References 4 publications

The vapour-liquid interface for a Lennard-Jones model of argon-krypton mixtures

The vapour-liquid interface for a Lennard-Jones model of argon-krypton mixtures

Test-area simulation method for the direct determination of the interfacial tension of systems with continuous or discontinuous potentials

Thermodynamic properties of the 3D Lennard-Jones/spline model

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