Statistical-Mechanical Theory of the Ripple Phase of Lipid Bilayers

We present the results of Monte Carlo simulations for a variant of the chiral clock model in an attempt to clarify the microscopic origins of the ripple (${\mathrm{P}}_{\mathrm{\beta }\prime }$) phase that occurs in cewrtain lipid bilayers. Using independently determined values of the molecular interactions the simulations exhibit a ripple phase whose properties are in good agreement with certain features of synchrotron x-ray data and scanning tunneling micrographs of the ${\mathrm{P}}_{\mathrm{\beta }\prime }$ phase. The simulation data are compared to mean-field results which suggest the possibility that the ripple phase of the model is metastable. © 1990 The American Physical Society