Orientational phase transition and the solvation force in a nematic liquid crystal confined between inhomogeneous substratesS. Kondrat1, A. Poniewierski1 and L. Harnau2, 3
1 Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
2 Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart, Germany
3 Institut für Theoretische und Angewandte Physik, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
(Received 12 November 2002 Published online: 16 April 2003 )
A nematic liquid crystal confined between two identical flat solid substrates, with an alternating stripe pattern of planar and homeotropic anchoring, is studied in the framework of the Frank-Oseen theory. By means of numerical minimization of the free energy functional we study the effect of the sample thickness D on the location of the phase transition between a uniform alignment, either planar or homeotropic, and a distorted nematic texture. The solvation force f due to distortions of the nematic director is also studied. It is found that f is always attractive, and for D small compared to the periodicity of the surface structure it exhibits two distinct asymptotic behaviors: or , depending on the relation between D and the extrapolation lengths.
64.70.Md - Transitions in liquid crystals.
61.30.Cz - Molecular and microscopic models and theories of liquid crystal structure.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2003