Internal lipid bilayer friction coefficient from equilibrium canonical simulations

TL;DR

This paper derives the interleaflet friction coefficient of lipid bilayers using a generalized Einstein relation, emphasizing the importance of system constraints in equilibrium simulations.

Contribution

It introduces a novel method to calculate lipid bilayer friction coefficients from equilibrium simulations through a generalized Einstein relation.

Findings

Derived a practical approach for calculating lipid bilayer friction.

Highlighted the importance of system constraints in equilibrium simulations.

Provided a theoretical foundation linking friction to equilibrium properties.

Abstract

A fundamental result in the theory of Brownian motion is the Einstein-Sutherland relation between mobility and diffusion constant. Any classical linear response transport coefficient obeys a similar Einstein-Helfand relation. We show in this work how to derive the interleaflet friction coefficient of lipid bilayer by means of an adequate generalisation of the Einstein relation. Special attention must be paid in practical cases to the constraints on the system center of mass position that must be enforced when coupling the system to thermostat.