Oscillation Modes of Nematic Liquid Crystals

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Abstract
A novel self-contained two-dimensional contiuum theory for thin nematic liquid crystal layers has been developed. The theory, which is quasistatic in nature, predicts spatially varying oscillations of the molecular axes in modal striated patterns in response to an ac electric field. An oscillation threshold voltage is derived which increases with increased frequency of excitation. Also, the theory predicts that the spatial frequency of threshold striations increases similarly with increased frequency of excitation. These experimentally observed threshold effects are predicted without the introduction of shear torques, which have been of importance in earlier one-dimensional treatments of the problem, including hydrodynamic effects. The present theory includes torques arising from dielectric and conductivity anisotropy, curvature elastic torques, and dissipative torques determined by a curvature viscosity.