Dynamic implicit-solvent coarse-grained models of lipid bilayer membranes: Fluctuating hydrodynamics thermostat

摘要

We introduce a thermostat based on fluctuating hydrodynamics for dynamic simulations of implicit-solventncoarse-grained models of lipid bilayer membranes. We show our fluctuating hydrodynamics approach capturesninteresting correlations in the dynamics of lipid bilayermembranes that aremissing in simulations performed usingnstandard Langevin dynamics. Our momentum conserving thermostat accounts for solvent-mediated momentumntransfer by coupling coarse-grained degrees of freedom to stochastic continuum fields that account for both thensolvent hydrodynamics and thermal fluctuations. We present both a general framework and specific methodsnto couple the particle and continuum degrees of freedom in a manner consistent with statistical mechanicsnand amenable to efficient computational simulation. For self-assembled vesicles, we study the diffusivity ofnlipids and their spatial correlations. We find the hydrodynamic coupling yields within the bilayer interestingncorrelations between diffusing lipids that manifest as a vortex-like structure similar to those observed in explicitsolventnsimulations. We expect the introduced fluctuating hydrodynamics methods to provide a way to extendnimplicit-solvent models for use in a wide variety of dynamic studies.