On the existence of even indexed disclinations in nematic liquid crystals

The stability of cylindrically symmetrical line disclinations is examined by continum theory calculations and topological arguments, to show that these singularities can almost always be replaced by a continuous structure of lower energy. The calculations are applied to the four basic types of index ± 2 structures. Experimental observations are presented to support the proposed continuous structures as seen in cylindrical samples, and in the classical structures a fils and a noyaux.