Hybrid Particle-Field Molecular Dynamics Simulations of Charged Amphiphiles in Aqueous Environment

We develop and test specific coarse-grained models for charged amphiphilic systems such as palmitoyloleoyl phosphatidylglycerol (POPG) lipid bilayer, and sodium dodecyl sulphate (SDS) surfactant in aqueous environment, to verify the ability of the hybrid particle-field method to provide a realistic description of polyelectrolyte soft-matter systems. The intramolecular interactions are treated by a standard molecular Hamiltonian and the non-electrostatic intermolecular forces are described by density fields. Electrostatics is introduced as an additional external field obtained by a modified particle-mesh Ewald procedure. Molecular dynamics simulations indicate that the methodology is robust with respect to the choice of the relative dielectric constant, yielding the same correct qualitative behavior for a broad range of dielectric values. In particular, our methodology reproduces well the organization of the POPG bilayer, as well as the SDS concentration-dependent change in the morphology of the micelles from spherical to microtubular aggregates.