Coupling between polarization, orientation, and chirality in smectic filmsformed by bent-shaped molecules

We formulate a simple Landau type model describing macroscopic behavior rec ently discovered in new smectic phases composed of achiral bent-shaped mole cules. Films of such smectics exhibit three types of ordering related to di pole polarization, molecular tilt, and chirality. However, due to specific third-order coupling of the order parameters, these three symmetry-breaking types are not independent and this fact leads to specific domain structure s that are observed in experiments. (C) 2000 MAIK "Nauka/Interperiodica".