Wall effect of director deformation in nematic liquid crystals

We discuss the director deformation near the interface between a liquid crystal and a solid substrate. The gradient of the tilt angle at the interface was measured by Sprokel et al. as a function of an applied voltage; they obtained a larger gradient than that calculated from Frank theory by a factor of about 5. In order to explain the abnormal gradient, we have taken into account the balance of torque at the interface. The gradient of tilt was estimated when the higher voltage is applied to the liquid crystals; the estimated result agrees well with their experimental result.