Influence of flexoelectricity above the nematic Fréedericksz transition.

Continuum theory is used to demonstrate that the presence of flexoelectricity significantly alters the response to an applied voltage of a homogeneous nematic liquid crystal cell above the ac Fréedericksz threshold voltage. In such a system there is a fitting degeneracy: we obtain very good fits between theory and experimental permittivity data using any value of the sum of flexoelectric coefficients, e(11)+e(33), between 0.0 C/m and 1.5 x 10(-11) C/m. The corresponding values of the nematic bend elastic constant show an inverse parabolic relationship with e(11)+e(33), with K33 being reduced down to 90% of its value when flexoelectricity is neglected.