Eur. Phys. J. E 10, 163-170 (2003)
DOI: 10.1140/epje/e2003-00020-3

Orientational phase transition and the solvation force in a nematic liquid crystal confined between inhomogeneous substrates

S. Kondrat¹, A. Poniewierski¹ and L. Harnau<sup>2, 3

1</sup>  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 )

Abstract
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.

PACS
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