TOPOLOGY OF SINGULAR LINES IN NON-CHIRAL SMECTICS

The principal configurations of curvilinear defects in smectic C phases are described on the basis of two classifications, by the Volterra process and by the classes of equivalence of the first homotopy group of the manifold of internal states of the ordered medium. These two classifications are compared. The purpose of this article is to show the use of these two classifications in the case of smectic C phases. These classifications do not allow a complete description of curvilinear defects. Consideration of energetics and topological interactions with defects of other dimensionalities must at least be added. Focal conics demand a widening of the discussion in this paper.