Monte Carlo simulation of the unwinding of cholesteric twist

The unwinding of cholesteric twist has been observed in liquid-crystalline DNA near the cholesteric-hexagonal columnar phase boundary. Disclination lines are seen to bound regions of different total twist. A Monte Carlo simulation, applying a molecular statistical model for the cholesteric phase, is used to model this unwinding and the disclination lines. We find disclination lines corresponding to edge χ lines. We also find evidence for λτ pairs. These results are in agreement with expectations from phenomenological Landau–de Gennes theory and homotopy. Furthermore, the results obtained can be used to describe the terraced morphology observed in the DNA system.