Head-Tail Asymmetry of a Molecule as a Microscopic Origin ofthe Successive Phase Transitions in Chiral Smectics

Abstract

The head-tail asymmetry is distinction between energy of a pair of rod-like molecules in head-to-head configuration and energy of the pair in tail-to-tail or head-to-tail configuration.We use a molecular model system to consider arole of the head-tail asymmetry for the phase transitions of chiral smectics.Mean field theory indicates that our model system shows the existence of various types of intermediate phases such as Sm-C^*_γ and AF phase betweenantiferroelectric Sm-C^*_A phase and ferroelectricSm-C^* phase.One of origins of the existence of the intermediate phasesis the ordering of heads which induce interactions betweenseparated smectic layers.