Energetics of screw dislocations in smectic A liquid crystals

We derive the self-energy of a single screw dislocation in smectic A liquid crystals allowing for bend curvature in the bulk. For the core region two models are investigated: a nematic one including bend and twist curvature and an isotropic one including surface curvature energy. The former is energetically favourable. For both models the interaction force between two parallel screw dislocations is zero within the linear theory. Taking into account non-linearities perturbatively, an interaction potential is obtained, which is proportional to the logarithm of the distance of the screw dislocations.