Lennard-Jones fluid phase behavior

Fig. 10.12. Vapor-liquid phase behavior for the Lennard-Jones fluid. Solid triangles and hollow squares indicate the results of the particle addition/deletion and volume scaling variants of the flat-histogram simulation using the Wang-Landau algorithm. Crosses are from a histogram reweighting study based on grand-canonical measurements at seven state points. The solid line is from Lotfi, et al. [76], Reprinted figure with permission from [75]. 2002 by the American Physical Society...

An efficient method of solving the Percus-Yevick and related equations is described. The method is applied to a Lennard-Jones fluid, and the solutions obtained are discussed. It is shown that the Percus-Yevick equation predicts a phase change with critical density close to 0.27 and with a critical temperature which is dependent upon the range at which the Lennard-Jones potential is truncated. At the phase change the compressibility becomes infinite although the virial equation of state (foes not show this behavior. Outside the critical region the PY equation is at least two-valued for all densities in the range (0, 0.6). 

J. E. Hunter and W. P. Reinhardt (1995) Finite-size-scaling behavior of the free-energy barrier between coexisting phases - determination of the critical-temperature and interfacial-tension of the Lennard-Jones fluid. J. Chem. Phys. 103, pp. 8627-8637... 

The phase behavior of the Lennard-Jones fluid has been studied extensively in the past. It therefore provides an ideal example for examining the... 

In somewhat earlier work, Vlot et al. [229,230] made calculations of Lennard-Jones binary mixtures in which the pure components are identical but in which the unlike interactions have departures from the Lorentz-Berthelot combining rules. They use this as a model of mixtures of enantiomers. A variety of solid-fluid phase behavior can be obtained from the model. Both substitutionally ordered and substitutionally disordered solid solutions were found to occur. 

The existence of two competing local structures may appear as an essential condition for the occurrence of anomalous phase behaviors in general, and of LLPT in particular. To investigate if this is actually the case, we wish to examine models of CS fluids in which the soft repulsion is made progressively weaker and weaker so as to explore the behavior of systems with features intermediate between CS fluids with two distinct length scales and standard simple fluids with only one length scale (such as, e.g., the Lennard-Jones fluid). 

Mi J, Tang Y, Zhong C, Li Y-G Prediction of phase behavior of nanoconfined Lennard-Jones fluids with density functional theory based on the first-order mean spherical approximation, J Chem Phys 124(14) 144709, 2006. 

Behavior of the Free-Energy Barrier between Coexisting Phases—Determination of the Critical Temperature and Interfacial Tension of the Lennard-Jones Fluid. 

Motivated by a puzzling shape of the coexistence line, Kierlik et al. [27] have investigated the model with Lennard-Jones attractive forces between fluid particles as well as matrix particles and have shown that the mean spherical approximation (MSA) for the ROZ equations provides a qualitatively similar behavior to the MFA for adsorption isotherms. It has been shown, however, that the optimized random phase (ORPA) approximation (the MSA represents a particular case of this theory), if supplemented by the contribution of the second and third virial coefficients, yields a peculiar coexistence curve. It exhibits much more similarity to trends observed in... 

Potoff, J. J. Panagiotopoulos, A. Z., Critical point and phase behavior of the pure fluid and a Lennard-Jones mixture, J. Chem. Phys. 1998,109,10914—10920... 

We propose the study of Lennard-Jones (LJ) mixtures that simulate the carbon dioxide-naphthalene system. The LJ fluid is used only as a model, as real CO2 and CioHg are far from LJ particles. The rationale is that supercritical solubility enhancement is common to all fluids exhibiting critical behavior, irrespective of their specific intermolecular forces. Study of simpler models will bring out the salient features without the complications of details. The accurate HMSA integral equation (Ifl) is employed to calculate the pair correlation functions at various conditions characteristic of supercritical solutions. In closely related work reported elsewhere (Pfund, D. M. Lee, L. L. Cochran, H. D. Int. J. Thermophvs. in press and Fluid Phase Equilib. in preparation) we have explored methods of determining chemical potentials in solutions from molecular distribution functions. 

In order to extract the phase behavior and the properties of bubbles from the simulation data, one faces two problems (i) The insertion of whole chains has a rather small acceptance rate at high densities and is considerably more computationally demanding than the corresponding MC move in a simple liquid (e.g a Lennard-Jones monomer fluid or a lattice model). This gives rise to protracted long relaxation times and restricts us to rather small system sizes. In the vicinity of critical points in the... 

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