A classical density functional theory for solvation across length scales.

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Statistical Mechanics

Background:

• Multiscale modeling aims to bridge quantum mechanics (Schrödinger equation) with macroscopic phenomena.
• Classical density functional theory (cDFT) is a powerful tool for studying fluids and solvation.
• Hydrophobicity is a key phenomenon in solvation, particularly for apolar solutes.

Purpose of the Study:

• To develop a novel cDFT approach for accurate, multiscale solvation modeling of apolar solutes.
• To build upon and simplify existing theories like Lum-Chandler-Weeks (LCW) theory.
• To incorporate critical drying physics into a cDFT framework for a more complete hydrophobicity description.

Main Methods:

• Developed a new free energy functional based on a slowly varying density field reference.
• Utilized classical density functional theory (cDFT).
• Parameterized the theory using the uniform fluid's two-body direct correlation function and liquid-vapor surface tension.

Main Results:

• The new cDFT approach accurately describes apolar solute solvation across various length scales.
• The method is numerically simpler and more adaptable to soft-core repulsions than LCW theory.
• The theory successfully captures the physics of critical drying and temperature-dependent solvation.

Conclusions:

• The proposed LCW-style cDFT provides a robust and computationally efficient framework for multiscale solvation studies.
• This approach offers a first-principles description of solvation at length scales beyond molecular simulations.
• The inclusion of critical drying physics enhances the understanding of hydrophobicity.