Is perturbation DFT approach applicable to purely repulsive fluids?

Area of Science:

• Statistical Mechanics
• Computational Physics
• Physical Chemistry

Background:

• Perturbation Density Functional Theory (DFT) is a key tool for modeling fluid behavior.
• Understanding purely repulsive fluids under external fields is crucial for various applications.
• Accurate theoretical models are needed to complement simulation data.

Purpose of the Study:

• To evaluate a third order + second order perturbation DFT approach for purely repulsive model fluids.
• To assess the approach's validity and applicability under external fields.
• To compare theoretical DFT predictions with simulation data.

Main Methods:

• Utilized hard core repulsive Yukawa, point particle Yukawa, and inverse power potentials.
• Employed a third order + second order perturbation density functional theory (DFT).
• Validated results against grand canonical ensemble Monte Carlo simulations.

Main Results:

• The DFT approach showed suitability for purely repulsive fluids when using highly accurate bulk second-order direct correlation functions (DCF).
• The performance mechanism differs from mean-field approximations for van der Waals fluids.
• The bulk second-order DCF's density dependence is critical for hard-core interactions.

Conclusions:

• The tested perturbation DFT method is applicable to purely repulsive fluids under specific conditions.
• High accuracy in the bulk second-order DCF is essential for reliable DFT predictions.
• The study highlights the nuanced behavior of DCF in repulsive systems.