Communication: Consistent picture of lateral subdiffusion in lipid bilayers: Molecular dynamics simulation and exact results

• DOI: 10.1063/1.3651800
• Publication Date: 2011-10-12T22:56:39Z
• Authors: Gerald R. Kneller; Krzysztof Baczynski; Marta Pasenkiewic...
• Keywords: MOTION; Lipid Bilayers; Molecular Dynamics Simulation; [INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation; 01 natural sciences; DIFFUSION; CELL-MEMBRANE; FLUORESCENCE CORRELATION SPECTROSCOPY; Diffusion; TRACKING; 0103 physical sciences; Phosphatidylcholines

This communication presents a molecular dynamics simulation study of a bilayer consisting of 128 dioleoyl-sn-glycero-3-phosphocholine molecules, which focusses on the center-of-mass diffusion of the lipid molecules parallel to the membrane plane. The analysis of the simulation results is performed within the framework of the generalized Langevin equation and leads to a consistent picture of subdiffusion. The mean square displacement of the lipid molecules evolves as ∝ tα, with α between 0.5 and 0.6, and the fractional diffusion coefficient is close to the experimental value for a similar system obtained by fluorescence correlation spectroscopy. We show that the long-time tails of the lateral velocity autocorrelation function and the associated memory function agree well with exact results which have been recently derived by asymptotic analysis [G. Kneller, J. Chem. Phys. 134, 224106 (2011)10.1063/1.3598483]. In this context, we define characteristic time scales for these two quantities.