Thermal fluctuations in a lamellar phase of a binary amphiphile–solvent mixture: A molecular-dynamics study.

We investigate thermal fluctuations in a smectic A phase of an amphiphile–solvent mixture with molecular-dynamics simulations. We use an idealized model system, where solvent particles are represented by simple beads, and amphiphiles by bead-and-spring tetramers. At a solvent bead fraction of 20% and sufficiently low temperature, the amphiphiles self-assemble into a highly oriented lamellar phase. Our study aims at comparing the structure of this phase with the predictions of the elastic theory of thermally fluctuating fluid membrane stacks [Lei et al., J. Phys. II 5, 1155 (1995)]. We suggest a method which permits to calculate the bending rigidity and compressibility modulus of the lamellar stack from the simulation data. The simulation results are in reasonable agreement with the theory. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]