Beschreibung:
<jats:p>
The specific features characterizing the phenomenological approach to phase transitions in liquid crystals, are discussed. The identification of the phase symmetries is shown to require, in addition to the space-group of the phases, specification of the type of long-range bond-orientational and tilting orderings of the molecular subunits. The probability densities and irreducible degrees of freedom corresponding to transitions between mesomorphic phases are explicited. A Landau type symmetry analysis is performed for illustrative examples of transitions from a nematic and smectic phases.
</jats:p>