Articles you may be interested inStructure of penetrable sphere fluids and mixtures near a slit hard wall: A modified bridge density functional approximation Structures and correlation functions of multicomponent and polydisperse hard-sphere mixtures from a density functional theoryThe density functional theory ͑DFT͒ based on the bridge density functional and the fundamental-measure theory ͑FMT͒ have been used to investigate the structural properties of oneand two-component penetrable spheres in a spherical pore. The Monte Carlo simulations have been carried out to compare with the theoretical results. The result shows that at low temperature the FMT functional is better than the DFT based on the bridge density functional and compares well with the computer simulations. At high temperature the DFT based on the bridge density functional is better than the FMT functional. These results suggest the reliable accuracy of the modified Verlet closure for the penetrable spheres at high temperature. However, the accuracy of both the FMT functional and the DFT based on the bridge density functional deteriorates if the packing fraction is increased.
A density functional perturbation approximation (DFPT), which is based both on the fundamental-measure theory (FMT) to the hard-sphere repulsion and on the weighted-density approximations (WDAs) to the attractive contribution, has been proposed for studying the structural properties of model fluids with an attractive part of the potential. The advantage of the present theory is the simplicity of the calculation of the weight function due to the attractive contribution. It has been applied to predict the equilibrium particle density distributions and adsorption isotherms of Lennard-Jones fluids at interfaces. The theoretical results show that the present theory describes quite well the adsorption isotherms of a Lennard-Jones ethane in a graphite slit pore as well as the equilibrium particle density distributions of a Lennard-Jones fluid near a planar slit pore.
A density functional approximation, which is based on both the density functional Taylor series expansion of the one-particle direct correlation function and the exact contact value theorem for a hard wall, has been proposed to study the structural properties of confined classical fluids. The approximation has been applied to calculate the density profiles of sticky hard-sphere fluids confined in structureless hard walls. The calculated density profiles have shown that the present approximation compares very well with the results from the computer simulation. Furthermore, a density functional perturbative approximation, which is based on both the weighted-density approximation for the repulsive part of potential and the present approximation for the attractive part of potential, has been developed to predict the density profiles of model fluids with the attractive part of potential and has been applied to calculate the density profiles of hard-sphere Yukawa fluids near a planar slit. The calculated results also show that the proposed perturbative approximation is a significant improvement upon those of the modified version of the Lovett-Mou-Buff-Wertheim, and compares very well with the computer simulation. ͓S1063-651X͑98͒04210-X͔ PACS number͑s͒: 61.20.Gy, 61.20.Ne
Molecular dynamics simulations are carried out to investigate the diffusion behavior of penetrable-sphere model fluids characterized by a finite energy barrier ϵ. The self-diffusion coefficient is evaluated from the time-dependent velocity autocorrelation function and mean-square displacement. Detailed insights into the cluster formation for penetrable spheres are gained from the Enskog factor, the effective particle volume fraction, the mean free path, and the collision frequency for both the soft-type penetrable and the hard-type reflective collisions. The simulation data are compared to theoretical predictions from the Boltzmann kinetic equation and from a simple extension to finite ϵ of the Enskog prediction for impenetrable hard spheres (ϵ→∞). A reasonable agreement between theoretical and simulation results is found in the cases of ϵ∗ ≡ ϵ/k(B)T=0.2, 0.5, and 1.0. However, for dense systems (packing fraction ϕ>0.6) with a highly repulsive energy barrier (ϵ∗ = 3.0), a poorer agreement was observed due to metastable static effects of clustering formation and dynamic effects of correlated collision processes among these cluster-forming particles.
New hybrid weighted-density approximations (HWDA) based an both local and global average densities are proposed. In one of the approximtions the weighting function is constructed to satisfy the same homogeneous properties as the local weighted-density approximation (LWDA) proposed by Tanrona, in the other, the weighting function is consuueted to agree with that of Leidl and Wagner for the homogeneous fluid, Free energy functianals arr derived from these proposed weighted-density approximations by using expansions in term of the density. They are applied to predict the density profiles of hard-sphere fluids restricted by hard and permeable walls and in spherical cages, For the density profiles of fluids confined between hard Rat walls, the results are in good agreement with the computer simulations and comparable with those of the free energ). functiooal approximation of 'Tarawna even at the high density po3 = 0.9135. For the density profiles of h&-sphere fluids restricted by permeable walls with a finite height and in spherical cages, the results are also in good agreement with the computer simulations. These results show that although the free energy functionals differ, the new approximations and LWDA produce equally accurate results for the inhomogeneous hard-sphere fluids investigated. The new approvtmalions have the advantage of being simpler to apply.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.