Collective phenomena in lipid membranes, like pore formation and fusion, selfassembly, or lateral demixing of lipid mixtures, have attracted tremendous interest over the last years. Often, collective phenomena involve mesoscopic time and length scales, microseconds and micrometers, which are difficult to observe directly in experiments and which are at present beyond the scales that can be addressed by models with atomistic resolution. The reduced number of degrees of freedom and the softer potentials in coarse-grained models open up the opportunity to address the mesoscopic scales computationally and to gain qualitative insights.
In this work we present a solvent-free, coarse-grained model for amphiphilic bilayers. The molecules are represented by linear bead-spring chains and the non-bonded interactions are derived from a classical density functional, which is an expansion of the free energy in terms of weighted molecular densities up to third order. Within the mean-field approximation the involved expansion coefficients and weighting functions can be utilized to tune the equation of state and the local, fluid structure of the model independently. We employ Dissipative Particle Dynamics (DPD) simulations to study the properties of the model numerically.