The behavior of fluids near solutes: a density functional theory and computer simulation study

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Soft Matter Physics

Background:

• Understanding solvent behavior around solutes is crucial for various chemical and physical processes.
• The hydrophobic effect, a key phenomenon in biological and chemical systems, influences molecular interactions and self-assembly.
• Existing theories, like the Lum, Chandler, and Weeks (LCW) approach, provide frameworks for studying these effects.

Purpose of the Study:

• To investigate the density distribution of solvent molecules around a solute particle.
• To explore the influence of solute size on solvent ordering and phase behavior.
• To compare the accuracy of density functional theory (DFT) with existing models for the hydrophobic effect.

Main Methods:

• Utilizing density functional theory (DFT) combined with Monte Carlo (MC) simulations.
• Modeling fluid-fluid interactions with a hard sphere plus Yukawa potential.
• Modeling solute-solvent interactions with a hard sphere potential.

Main Results:

• Observed liquid-like solvent ordering near small solute particles.
• Identified a drying transition for larger solutes near solvent coexistence conditions.
• Demonstrated that DFT provides quantitatively more accurate predictions than the LCW approach.

Conclusions:

• DFT and MC simulations accurately capture solvent ordering and drying transitions around solutes.
• The study establishes a quantitative link between DFT methods and the LCW approach.
• Findings offer improved theoretical insights into the hydrophobic effect and solvent-solute interactions.