On the stability of the isotropic phase towards nematic and smecticAformation

Abstract

A new stability condition governing the formation of liquid crystalline phases of various degrees of orientational or translational ordering and supplementing the standard conditions of mechanical or thermal stability of a phase, is applied to the specific example of formation of a smectic A or a nematic phase from an isotropic phase. Numerical results are shown for a molecular model of hard spherocylinders with an r ^-6 centre-to-centre attraction. Such molecules should form smectic A phases and the smectic range for which the stability breaks first, is of reasonable order of magnitude. The effect of temperature and the length of the molecule is examined.