CURVATURE ELASTICITY OF SMECTIC-A TEXTURES WITH VIRTUAL SURFACE SINGULARITIES

Smectic-A textures limited by special boundaries which do not fix the layer positions but only the direction of the layer normals should obey a simplified elasticity. This elasticity involves no layer dilation but only curvature energy. We present it for smectics limited to planar cells, when all the singularities due to the absence of layer dilation are virtual. We show the possibility of anchoring transitions at low threshold and the existence of a universal cycloid shape in the absence of external constraints. The link with the nucleation of smectic focal conics is discussed.