Molecular dynamics simulation of the liquid crystalline semiconductor: 8-TTP-8

In this study, the structure and dynamics of a liquid crystalline semiconductor dioctylterthiophene system, 8-TTP-8, were examined by molecular dynamics simulations. We especially focus on the melting transition from the crystal to the liquid crystal smectic G phase. Simulations of the rotational autocorrelation function show that the transition is characterized by the onset of rotation around the long molecular axis, while maintaining a hexagonal packing within the smectic layers. This implies that the stepwise decrease of the carrier mobility at the melting transition point may be caused by this rotational disordering. We also found the molecular diffusions (at a rate of D similar to 0.9 x 10-(10)m(2)/s) in the simulated SmG phase. All these characteristics of the simulated SmG phase, including the molecular diffusions, are similar to those of a rotator (plastic crystal) phase.