A meso-scale analysis of lipid bilayers with the dissipative particle dynamics method: Thermally fluctuating interfaces

摘要

We present a meso-scale simulation of lipid bilayers with the dissipative particle dynamics (DPD) method. The spectrums of the thermal undulation are analysed and the bending rigidity of the lipid bilayers is calculated. In order to define the position of the membrane, we apply a definition of the interface which has been newly proposed by Kikugawa et al. (Comput. Fluids 2007; 36:69-76). We show the applicability of this method to the lipid bilayer system. By means of this definition, the roughness of the extracted interface can be varied and this effect is investigated. The spectral intensity is shown as a function of the undulatory wave-number q. The spectral intensity in large-q regions is affected by the roughness of the interface. However, we find that the spectral intensity in small-q regions, where the bending rigidity can be calculated, is hardly affected. Moreover, the undulation spectrums show q{sup}(-4) behaviour in small-q regions, which agrees with the theoretical prediction. The effects of the size of the computational cell are also investigated. All spectrums obtained in the differently sized cells agree well, although the observable range of the wave-number depends on the cell size. The bending rigidity calculated by spectral intensity from the largest cell is in good agreement with experiments and molecular dynamics simulations in the literature.