Development of theories of inhomogeneous fluids, J.S. Rowlinson statistical mechanical sum rules, J.R. Henderson density functionals in the theory of non-uniform fluids, R. Evans integral equation theories for inhomogeneous fluids, Douglas Henderson inhomogeneous two-dimensional plasmas, B. Jancovici statistical mechanics of electrolytes at interfaces, L. Blum and Douglas Henderson wetting experiments, Carl Franck fluids between walls and in pores, Marcelo Lozada-Cassou freezing, A.D.J. Haymet nucleation, David W. Oxtoby liquid crystals, J.F. Marko nature of microemulsion, K.A. Dawson and Christopher J. Mundy kinetic theory of strongly inhomogeneous fluids, H. Ted Davis.

Fundamentals of Inhomogeneous Fluids

Nucleation and Growth of Nanoparticles in the Atmosphere Renyi Zhang,* Alexei Khalizov, Lin Wang, Min Hu, and Wen Xu Department of Atmospheric Sciences andDepartment of Chemistry, Center for Atmospheric Chemistry and Environment, Texas A&M University, College Station, Texas 77843, United States Department of Environmental Science & Engineering and Institute of Global Environment Change Research, Fudan University, Shanghai 200433, China State Key Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China

Nucleation and Growth of Nanoparticles in the Atmosphere

We report a computer-simulation study of homogeneous gas–liquid nucleation in a Lennard-Jones system. Using umbrella sampling, we compute the free energy of a cluster as a function of its size. A thermodynamic integration scheme is employed to determine the height of the nucleation barrier as a function of supersaturation. Our simulations illustrate that the mechanical and the thermodynamical surfaces of tension and surface tension differ significantly. In particular, we show that the mechanical definition of the surface tension cannot be used to compute this barrier height. We find that the relations recently proposed by McGraw and Laaksonen [J. Chem. Phys. 106, 5284 (1997)] for the height of the barrier and for the size of the critical nucleus are obeyed.

/pdf/computer-simulation-study-of-gas-liquid-nucleation-in-a-1gl7twqavi.pdf

Computer simulation study of gas–liquid nucleation in a Lennard-Jones system

Canonical molecular dynamics (MD) and Monte Carlo (MC) simulations for liquid/vapor equilibrium in truncated Lennard-Jones fluid have been carried out. Different results for coexistence properties (orthobaric densities, normal and tangential pressure profiles, and surface tension) have been reported in each method. These differences are attributed in literature to different set up conditions, e.g., size of simulation cell, number of particles, cut-off radius, time of simulations, etc., applied by different authors. In the present study we show that observed disagreement between simulation results is due to the fact that different authors inadvertently simulated different model fluids. The origin of the problem lies in details of truncation procedure used in simulation studies. Care has to be exercised in doing the comparison between both methods because in MC calculations one deals with the truncated potential, while in MD calculations one uses the truncated forces, i.e., derivative of the potential. The truncated force does not uniquely define the primordial potential. It results in MD and MC simulations being performed for different potential models. No differences in the coexistence properties obtained from MD and MC simulations are found when the same potential model is used. An additional force due to the discontinuity of the truncated potential at cut-off distance becomes crucial for inhomogeneous fluids and has to be included into the virial calculations in MC and MD, and into the computation of trajectories in MD simulations. The normal pressure profile for the truncated potential is constant through the interface and both vapor and liquid regions only when this contribution is taken into account, and ignoring it results in incorrect value of surface tension.

https://web.mst.edu/~hale/argonMC/References/JCP.1999.Trokhymchuk.LJ.liq.sim.Tc.pots..pdf

Computer simulations of liquid/vapor interface in Lennard-Jones fluids: Some questions and answers

We use density functional methods to develop a new nonclassical theory for the homogeneous nucleation of the gas to liquid phase transition. The extent of agreement between our results and the classical prediction of Becker, Doring, and Zeldovich is strongly dependent on the range of the attractive potential which we employ. We show that our predictions are consistent with experimental data using cloud chambers, and we suggest several directions in which experimentalists might look in order to find nonclassical effects. In particular, we suggest that cavitation (gas bubble formation in a liquid subjected to tensile stress) should nucleate at a significantly greater rate than that predicted by classical theory.

Nonclassical nucleation theory for the gas-liquid transition

We report a molecular dynamics study of the planar vapour-liquid interface for mixtures of Ar and Kr modelled by truncated Lennard-Jones 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 concentr...

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

We have studied the interfacial properties of droplets of (cutoff and shifted) Lennard‐Jones fluids in the canonical ensemble, using mean field theory. We have examined the effects of system size, overall density (supersaturation) and temperature on the density profiles, density and pressure at the center of the droplet, and surface tension. The numerical accuracy of the theory was tested by extensive comparisons of the results with the molecular dynamics simulations of Thompson et al. Good agreement was found. We have used the theory to calculate the energy of formation of a droplet and the stability temperature Ts for droplet formation as a function of the system size and overall density. We find Ts to be lower than the coexistence temperature for the planar surface, and to fall as the drop size falls.

A microscopic theory for spherical interfaces: Liquid drops in the canonical ensemble

Etudes de l'interface liquide-vapeur d'un melange de composants A et B, ou A est le solvant liquide et B est le solute volatil (souvent hypercritique), a l'aide de la methode de simulation de dynamique moleculaire (DM) et de la theorie du champ moyen (TCM). Dans de tels melanges le composant volatile B est souvent fortement adsorbe sur la surface, ce qui entraine une forte reduction de la tension superficielle. Calcul a l'aide de DM des profils de densite, de l'adsorption et de la tension superficielle pour de tels melanges composes de molecules de Lennard-Jones et comparaisons des resultats avec ceux obtenus par TCM

D. J. Lee

Papers

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

A microscopic theory for spherical interfaces: Liquid drops in the canonical ensemble

Adsorption and surface tension reduction at the vapor-liquid interface

Tunable emission properties of Eu ions in KBPO4 (B = Ca, Sr, and Ba) via variation in their valence states

Co-Doping Effect of CE Ions on EU Ion-Doped Sr2sno4 in Terms of Emission Color Tunability and Intensity Modulation