Macroscopic electrostatic potentials and interactions in self-assembled molecular bilayers: the case of Newton black films

TL;DR

This paper introduces a simplified yet detailed model of amphiphilic bilayers that accurately captures electrostatic interactions, including higher order moments, and demonstrates its effectiveness through molecular dynamics simulations of Newton black films.

Contribution

A new macroscopic electrostatic model for bilayers that includes higher order moments and is computationally efficient for MD simulations.

Findings

Model accurately captures electrostatic interactions in bilayers.

Superposition of gaussians enables analytical integration of the electrostatic field.

Simulation results validate the model's effectiveness.

Abstract

We propose a very simple but 'realistic' model of amphiphilic bilayers,simple enough to be able to include a large number of molecules in the sample, but nevertheless detailed enough to include molecular charge distributions, flexible amphiphilic molecules and a reliable model of water. All these parameters are essential in a nanoscopic scale study of intermolecular and long range electrostatic interactions. We also propose a novel, simple and more accurate macroscopic electrostatic field for model bilayers. This model goes beyond the total dipole moment of the sample, which on a time average is zero for this type of symmetrical samples, i. e., it includes higher order moments of this macroscopic electric field. We show that by representing it with a superposition of gaussians it can be 'analytically' integrated, and therefore its calculation is easily implemented in a MD simulation (even in simulations of non-symmetrical bi- or multi-layers). In this paper we test our model by molecular dynamics simulations of Newton black films.