  The liquid crystalline model biomembrane system consisting of a stack of
interacting membranes is studied by the newly developed Fourier Monte Carlo
simulation technique. In comparison to perturbation theory, substantial
quantitative discrepancies are found that affect determination of interbilayer
interactions. A harmonic theory is also routinely used to interpret x-ray
scattering line shapes; this is shown to be valid because the distance
dependence of the simulated correlation functions can be fairly well fit by the
harmonic theory.
