Computer simulations of bilayer membranes: Self-assembly and interfacial tension

TLDR

Binary Lennard‑Jones fluids of solvent and surfactant molecules serve as simplified models for amphiphilic molecules in solution. The authors use Monte Carlo and molecular dynamics simulations to observe surfactant self‑assembly into bilayer membranes and to measure their interfacial tension and compressibility modulus. The simulations reveal fluid bilayer membranes that self‑assemble from surfactants, exhibit rapid lateral diffusion, a tensionless state with a characterized stress profile, thereby bridging discrete atomic‑resolution and continuum smooth‑surface models.

Abstract

Binary Lennard-Jones fluids consisting of “solvent” and “surfactant” molecules are studied as simplified model systems for amphiphilic molecules in solution. Using Monte Carlo and molecular dynamics simulations, we observe the self-assembly of the surfactant molecules into bilayer membranes. These bilayers are fluid since the surfactants exhibit rapid lateral diffusion. We also measure the interfacial tension and the compressibility modulus of these bilayers. We show that they exhibit a tensionless state and characterize the corresponding stress profile. In this way, we bridge the gap between previous theoretical studies which were based (i) on discrete models with atomic resolution and (ii) on continuum models in which the bilayer membrane is treated as a smooth surface.