Order parameter theory for switching in antiferroelectric liquid crystals

In order to model the field induced switching of AFLC materials we have emp loyed a bilayer order parameter theory which includes changes in the distri bution of molecules around the smectic cone. The free energy is a function of the azimuthal director angle and the molecular order about this director in the odd and even layers. By minimizing the free energy the effective op tic axis may be calculated as a function of applied voltage. This theory is able to produce not only hysteretic tristate switching typical of AFLC mat erials but also the pre-transitional electroclinic-like behaviour at low fi eld strengths and the frequency dependence of the double hysteresis loop.