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Density functional theory of charged, hard-sphere fluids.
Dirk Gillespie1, Wolfgang Nonner, Robert S Eisenberg
1Department of Molecular Biophysics and Physiology, Rush University, 1750 West Harrison Street, Suite 1291, Chicago, Illinois 60612, USA. dirk_gillespie@rush.edu
Summary
A new electrostatic excess free energy functional for charged, hard sphere fluids is introduced. This method accurately predicts fluid behavior, even with significant density changes, by using a reference fluid density functional.
Area of Science:
- Physical Chemistry
- Statistical Mechanics
- Computational Fluid Dynamics
Background:
- Calculating electrostatic excess free energy in charged fluids is complex, especially with varying densities.
- Existing methods often struggle with systems exhibiting significant density heterogeneity.
Purpose of the Study:
- To develop a novel, approximate electrostatic excess free energy functional for charged, hard sphere fluids.
- To create a functional applicable to systems with both large and small density variations.
Main Methods:
- The study employs a perturbation method based on a bulk reference fluid (Rosenfeld method).
- It introduces a reference fluid density (RFD) functional, replacing bulk densities with particle density functionals.
- The first-order direct correlation function (DCF) is computed using input DCFs from the RFD functional.
Main Results:
- The proposed functional accurately reproduces Monte Carlo simulation results.
- The method allows flexibility in choosing the RFD functional for optimal approximation.
- It simplifies the complex problem of finding excess free energy functionals.
Conclusions:
- The new electrostatic functional offers an accurate and flexible approach for charged hard sphere fluids.
- This method is particularly advantageous for systems with inhomogeneous density profiles.
- The study provides a practical tool for simulating complex fluid systems.