Density Functional Theory for Small Systems: Hard Spheres in a Closed Spherical Cavity

1997 ◽  
Vol 79 (13) ◽  
pp. 2466-2469 ◽  
Author(s):  
A. González ◽  
J. A. White ◽  
F. L. Román ◽  
S. Velasco ◽  
R. Evans
Keyword(s):  
Density Functional Theory ◽  
Spherical Cavity ◽  
Density Functional ◽  
Hard Spheres ◽  
Functional Theory ◽  
Small Systems

DENSITY FUNCTIONAL THEORY AND FREEZING OF HARD SPHERES, BEYOND THE PERCUS–YEVICK APPROXIMATION

2007 ◽  
Vol 21 (07) ◽  
pp. 1089-1098 ◽  
Author(s):  
M. MORADI ◽  
A. RAZEGHIZADEH
Keyword(s):  
Density Functional Theory ◽  
Monte Carlo ◽  
Structure Factor ◽  
Hard Sphere ◽  
Density Functional ◽  
Hard Spheres ◽  
Spherical Approximation ◽  
Mean Spherical Approximation ◽  
Functional Theory ◽  
Weighted Density Approximation

The density functional theory for the freezing hard spheres is studied. We use a variety of the hard sphere direct correlation functions (DCFs) such as the one introduced by Roth et al. [J. Phys. Condens. Matter14, 12063 (2002)]; we call it RELK DCF, a new hard sphere DCF developed here by a combination of the RELK and the Percus–Yevick DCFs, and finally the generalized mean spherical approximation (GMSA). The structure factor, the freezing, and order parameters are calculated using these DCFs. The structure factor obtained by the new DCF is in good agreement with the Monte Carlo simulation. The best result for the freezing parameters in comparison with the Monte Carlo simulations is obtained by using our new expression for the DCF. Finally we obtain the Helmholtz free energy of the hard sphere FCC crystals using modified weighted density approximation (MWDA), and again the best results are obtained by using the new expression for the hard sphere DCF.

scholarly journals BEHAVIOR OF THE CONFINED HARD-SPHERE FLUID WITHIN NANOSLITS: A FUNDAMENTAL-MEASURE DENSITY-FUNCTIONAL THEORY STUDY

2008 ◽  
Vol 07 (04n05) ◽  
pp. 245-253 ◽  
Author(s):  
MOHAMMAD KAMALVAND ◽  
TAHMINEH (EZZAT) KESHAVARZI ◽  
G. ALI MANSOORI
Keyword(s):  
Density Functional Theory ◽  
Density Profile ◽  
Hard Sphere ◽  
Density Functional ◽  
Hard Spheres ◽  
Calculated Data ◽  
Computational Procedure ◽  
Functional Theory ◽  
Hard Sphere Fluid ◽  
Wide Range

A property of central interest for theoretical study of nanoconfined fluids is the density distribution of molecules. The density profile of the hard-sphere fluids confined within nanoslit pores is a key quantity for understanding the configurational behavior of confined real molecules. In this report, we produce the density profile of the hard-sphere fluid confined within nanoslit pores using the fundamental-measure density-functional theory (FM-DFT). FM-DFT is a powerful approach to studying the structure and the phase behavior of nanoconfined fluids. We report the computational procedure and the calculated data for nanoslits with different widths and for a wide range of hard-sphere fluid densities. The high accuracy of the resulting density profiles and optimum grid-size values in numerical integration are verified. The data reveal a number of interesting features of hard spheres in nanoslits, which are different from the bulk hard-sphere systems. These data are also useful for a variety of purposes, including obtaining the shear stress, thermal conductivity, adsorption, solvation forces, free volume and prediction of phase transitions.

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