Molecular theory of ferroelectric ordering in enantiomeric mixtures of smectic-C* liquid crystals.

A molecular theory of ferroelectric ordering in smectic-C* liquid crystals composed of left and right enantiomers is developed taking into account the effects of chiral discrimination. The recently observed nonlinear dependence of the spontaneous polarization on the enantiomeric excess is explained in the framework of a molecular model that takes into consideration the strong electrostatic interaction between effective atomic charges in the chiral centers of the two enantiomers. This nonlinear dependence is determined by a difference of interaction energies between the pairs of chiral molecules with equal and opposite handedness, respectively. A relation between the molecular structure of different ferroelectric smectics C* and the dependence of the polarization on the enantiomeric excess is discussed in detail.