On Model Independent Restoration of the Surface Anchoring Potential

Abstract

An analysis of various options to restore model independently the actual shape of the surface anchoring potential from the experimental measurements at chiral liquid crystals (CLC) is performed. It is shown that if the surface anchoring is sufficiently weak the restoration of the actual shape of the surface anchoring potential is achievable and there are some options to do this. The simplest option relates to the optical measurements at homogeneous layers of CLC under variation of some external parameter. Another possibility is connected with studying of the temporal development of the pitch jumps which occur in a homogeneous layer at some critical value of the external parameter. Additional options are presented by layers with nonsingular wall in the director distribution dividing two area differing by the pitch value: the director distribution in the wall is directly dependent on the surface anchoring potential. If a wall dividing two areas differing by the pitch value moves the motion velocity is also dependent on the surface anchoring potential and the corresponding measurements also may be applied for the restoration of the surface anchoring potential. The formulas for deriving of the angular derivative of the surface anchoring potential from the measurements related to the mentioned options are presented. The angular range of this derivative determination for the various studied options is estimated. The available experimental data are used to estimate the potential derivative and compare it with the derivative for the known model surface anchoring potentials.

Keywords:

• director dynamics
• nonsingular walls
• pitch jumps
• surface anchoring

Acknowledgments

The work is supported by the RFBR grant 06-02-16287.