Intrinsic torsional reorientations in a twisted nematic liquid crystal cell.
The nature of the orientational relaxation process of the director n to its equilibrium orientation neq, in the twisted nematic cell, under the influence of an external electric field, is investigated. The influence of the electric, elastic, and viscous torques on the dynamics of the director is reflected in the relaxation of the director n to neq, with different relaxation times. It is shown that the relaxation time, both for the cases of a strong and weak anchoring, exhibits an anomalous increase with decreasing of an external electric field, whereas the influence of the azimuthal anchoring energy, in the case of the twisted nematic cell is characterized by a weak effect. It is also shown that these torques exerted on the director may excite the traveling wave spreading from one edge of the cell to their second edge. Calculations of the relaxation processes in the vicinity of a nematic-smectic- A (NA) phase transition temperature T(NA) , e.g., at a few tens of mK from T(NA) in the nematic phase, shows that the director distortion in the gap between two plates is maintained to be constant across the sample both in the case of a strong and weak anchoring.
Zakharov
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Saint Petersburg Institute for Machine Sciences, The Russian Academy of Sciences, Saint Petersburg 199178, Russia. Alexandre.Zakhavor@fys.kuleuven.ac.be
Vakulenko
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AA