Soft fundamental measure theory functional for the Weeks-Chandler-Andersen repulsive potential

Area of Science:

• Statistical Mechanics
• Soft Matter Physics
• Computational Chemistry

Background:

• Classical density functional theory (DFT) often uses hard-sphere or square-well potentials as reference systems.
• Developing accurate reference systems for soft potentials is crucial for advancing DFT.
• The Weeks-Chandler-Andersen (WCA) potential models purely repulsive interactions, relevant for many soft matter systems.

Purpose of the Study:

• To introduce a novel soft fundamental measure theory (FMT) functional.
• To establish the Weeks-Chandler-Andersen (WCA) fluid as a viable reference system for DFT.
• To incorporate temperature-dependent parameters for accurate interaction modeling.

Main Methods:

• Developed a soft FMT functional tailored for the WCA potential.
• Incorporated temperature-dependent parameters for particle interaction length scale and softness.
• Validated the functional by reproducing the second virial coefficient of the WCA fluid.

Main Results:

• The proposed soft FMT functional accurately describes the WCA fluid.
• Temperature-dependent parameters effectively capture the interaction characteristics.
• The functional's accuracy is comparable to established methods like Barker-Henderson with White Bear DFT for hard spheres.

Conclusions:

• The developed soft FMT functional provides a robust reference system for soft potentials.
• This work offers a new avenue for creating more accurate DFTs for soft matter.
• The approach demonstrates the utility of FMT for modeling complex particle interactions.