Investigation of the frustration between ferroelectricity and antiferroelectricity in smectics

A molecular-statistical theory that describes the smectic phases with frustration between the ferroelectric and antiferroelectric ones has been developed. The molecular model is used to estimate the mean-field parameters responsible for the formation of complex smectic phases with long periods. A general phase diagram is constructed and the helix pitch is estimated in all phases. The results obtained are compared with the experimental ones.