Chapter Twelve - Thermal Fluctuations of Phospholipid Vesicles Studied by Monte Carlo Simulations

Abstract

Abstract This work presents the theoretical basis for Monte Carlo simulations of thermally fluctuating lipid bilayers. The purpose of such simulations is to obtain additional insight into the mechanical processes involved in thermal fluctuations of lipid bilayers and to test and limit some of the assumptions used in established theoretical models employed in measurements of the elastic properties of lipid membranes. The two-dimensional and three-dimensional models are explained and discussed. A dynamically triangulated surface model of the membrane is adapted to the thermally fluctuating vesicle with constant volume and local membrane stretching. The microstates of the vesicle are sampled according to the Metropolis algorithm, where fluctuations that conserve the volume of the vesicle are produced, while the energy of any given microstate of the vesicle consists of the bending and stretching energies of the vesicle. The vesicle shape is then approximated by a set of spherical harmonics. The results of the spectral analysis of thermally fluctuating vesicles in our simulations open questions that are discussed in the concluding section.