A MICROSCOPIC MODEL CONSIDERING THE EFFECT OF MOLECULAR BIAXIALITY ONFERROELECTRIC ORDERING OF LIQUID-CRYSTALLINE SMECTIC C-ASTERISK PHASES

On the basis of a mean-field approach, a microscopic model is presente d to explain some ferroelectric properties of induced smectic C phase s of chiral dipolar guest molecules in an achiral smectic C host phase . The molecular biaxiality of the chiral dopants has been taken into a ccount, resulting in a polar and quadrupolar ordering of the molecular short axes in the rotational distribution function of the guest molec ules. This model explains the dependence of the magnitude and sign of the spontaneous polarization on the molecular structure of a series of cyclohexanone derivatives used as chiral dopants, as well as the effe ct of a local field at higher dopant concentrations.