Fig. 2

Director configurations around two parallel twist disclination lines confined in a planar cell. a Configuration depicted according to Eq. (1) for the same handedness case. b Configuration of the opposite handedness case. Although the director of a nematic LC does not have a head–tail asymmetry, different colors are applied to highlight the differences in the topology of twist states. In a, the pair of the disclination lines separate the regions of ±π twisted states; in b, both sides of the disclination pair are untwisted, and the deformation is confined in the vicinity of the disclinations, which creates the attractive force between the disclination lines. The configuration in b is not in mechanical equilibrium without the aid of external force