A molecular density functional theory for associating fluids in 3D geometries

Area of Science:

• Physical Chemistry
• Statistical Mechanics
• Materials Science

Background:

• Understanding inhomogeneous fluids, especially those with associative interactions, is crucial for predicting material properties.
• Existing density functional theory (DFT) models face challenges in accurately describing complex fluid behaviors under confinement.

Purpose of the Study:

• To develop a new, tractable free-energy functional for inhomogeneous associating fluids within a DFT framework.
• To accurately model the microscopic structure and molecular bonding of associating fluids in 3D confined geometries.

Main Methods:

• Utilizing Wertheim's thermodynamic perturbation theory and statistical associating fluid theory hypotheses.
• Introducing specific weighted functions for association interactions, efficiently computed using Fourier transforms.
• Validating the model against Monte Carlo simulations for 1D systems and applying it to 3D zeolite-like cavities.

Main Results:

• The proposed functional accurately captures the behavior of inhomogeneous associating fluids.
• The model successfully predicts density distributions and molecular bonding profiles in complex 3D confinement.
• The study reveals the influence of association degree and steric effects on fluid adsorption and positioning.

Conclusions:

• The new free-energy functional provides a powerful tool for studying inhomogeneous associating fluids.
• The model offers insights into molecular organization and interactions within confined environments, relevant for nanotechnology and materials science.