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Abstract
The molecular-statistical theory of the ferroelectric smectic C* phase is summarized and generalued to the cases of the ferroelectric liquid crystals with large dipole in the chiral part of the molecule and to the mixtures of liquid crystals. The molecular model is proposed which is used to explain both ferroelectric and flexoelectric properties of the C* phase using a small number of molecular model parameters. In this model we consider the chiral intermolecular interaction, modulated by the banana-like shape of the molecules. The analysis of the model yields a simple chiral and polar interaction potential which is used in the statistical theory. The phenomenological constants of the smectic C* liquid crystals are expressed via the molecular model parameters.
In this report we consider also the microscopic interpretations of flexoelectricity in the smectic C phase. It is shown, that steric interaction of banana-like molecules results in the strong temperature dependence of flexoelectric coefficients. This result is used to explain the experimentally observed strong temperature variation of the helical pitch in the ferroelectric smectic C* phase.
