Attraction between like-charged walls: Short-ranged simulations using local molecular field theory

Area of Science:

• Colloid and Interface Science
• Statistical Mechanics
• Computational Physics

Background:

• Like-charged surfaces typically repel due to electrostatic forces.
• Counterion condensation can mediate effective attraction between charged surfaces.
• Local Molecular Field (LMF) theory provides a theoretical framework for such phenomena.

Purpose of the Study:

• To investigate the effective attraction between like-charged walls mediated by counterions using LMF theory.
• To validate the LMF theory by comparing its predictions with detailed simulations.
• To present a criterion for ensuring the accurate application of LMF theory.

Main Methods:

• Application of Local Molecular Field (LMF) theory.
• Monte Carlo simulations of a "mimic system" based on LMF theory.
• Comparison with existing simulations of full Coulomb systems.

Main Results:

• LMF theory accurately predicts effective attraction between like-charged walls.
• Simulations of the "mimic system" show excellent agreement with full Coulomb system simulations.
• A simple, general criterion for determining the LMF theory consistency parameter sigma(min) is established.

Conclusions:

• LMF theory is a reliable tool for studying counterion-mediated interactions between charged surfaces.
• The developed criterion simplifies and enhances the applicability of LMF theory.
• This work provides a robust method for understanding electrostatic interactions in confined geometries.