Mesoscale Electrostatics Driving Particle Dynamics in Nonhomogeneous Dielectrics

Area of Science:

• Computational chemistry and physics
• Soft matter science
• Electrostatics in condensed phases

Background:

• Accurate calculation of electrostatic interactions is crucial for understanding condensed phase systems.
• Existing methods often struggle with systems featuring spatially varying dielectric properties.
• Mesoscopic systems with molecular resolution require efficient and robust electrostatic formalisms.

Purpose of the Study:

• To introduce a novel density functional-based formalism for computing electrostatic energy and forces.
• To enable calculations for mesoscopic condensed phase systems at molecular resolution.
• To account for spatially variable dielectric permittivity dependent on particle density fields.

Main Methods:

• Developed a formalism based on density functional theory.
• Solved the generalized Poisson equation numerically to obtain electrostatic potential.
• Implemented a method with systematically controllable error via spatial grid resolution.

Main Results:

• Successfully reproduced concentration-dependent salt partitioning in water/oil mixtures, matching Born theory predictions (∝ 1/ϵ).
• Accurately captured electrostatic features of lipid bilayers, including membrane and dipole potentials.
• Demonstrated that Coulomb and polarization forces create a repulsive potential of mean force for ions within membranes.

Conclusions:

• The introduced method provides a robust and accurate way to compute electrostatic interactions in complex, heterogeneous systems.
• The formalism accounts for mesoscopic polarization forces arising from fluctuating dielectrics.
• Its computational efficiency makes it suitable for large-scale soft matter and polyelectrolyte systems.