A Theory of the Cholesteric Mesophase

Abstract

A theory of the macroscopic twist which is a characteristic feature of the cholesteric liquid crystal phase is proposed. This is based on the presence of anharmonicity in the forces resisting the relative twist of neighboring planes of molecules and views the macroscopic twist as the rotational analog of thermal expansion. On the basis of a simple mode for the harmonic part of the forces, the temperature dependence of the peak reflectance wavelength observed by Fergason et al. is well explained.