MOLECULAR-DYNAMICS SIMULATION OF THE SMECTIC-A-ASTERISK TWIST GRAIN-BOUNDARY PHASE

In this paper we present the results of extensive molecular-dynamics s imulations of a model of liquid crystals, in which a twist is imposed on the direction of preferred orientation. On quenching the system fro m a twisted nematic phase to a state point within the smectic-A phase, we observe a structure which corresponds closely to that of the smect ic-A twist grain-boundary phase. We investigate this structure by mea ns of director and structure factor profiles, and also develop a techn ique for automatically locating screw dislocations. Applying this tech nique to the configurations from our simulations, we obtain a defect d istribution which is in qualitative agreement with theoretical predict ions.