Coarse-grained simulations of lipid bilayers

A minimal model of lipid molecules consisting of bead-spring representation is developed. The basic interactions are hydrophobic and polar interactions. Essential physical features of lipid bilayers are maintained using this model, and relatively long times can be simulated in comparison to atomistic models. Self-assembly from a random starting configuration to a bilayer can readily be followed using molecular dynamics simulations. The diffusion of lipid molecules well beyond their nearest neighbors is attained. As a basis for description of the model, the area per lipid, the bending modulus, and the area compressibility as a function of temperature and tail length are calculated. A liquid to gel transition is observed and quantitatively characterized. Both saturated and unsaturated lipids are treated.