DOI: 10.1051/jp2:1991199
J. Phys. II France 1 (1991) 691-705

Surface order transition in nematic liquid crystals

G. Barbero¹, Z. Gabbasova² and M. A. Osipov<sup>3

1</sup>  Dipartimento di Fisica del Politecnico, Corso Duca degli Abruzzi 24, 10129 Torino, Italia
²  Theoretical Physics Department, Bashkir State University Frunze Street 32, 450074 UFA, U.S.S.R.
³  Institute of Crystallography, Lenninsky pr. 59, 117334 Moscow U.S.S.R.

(Received 27 December 1990, accepted in final form 22 February 1991)

Abstract
The surface order transition in nematic liquid crystals is theoretically analysed. Starting from a pseudo-molecular model it is shown that the so called anchoring energy has two contributions: one coming from the nematic-nematic interaction and another one coming from the nematic substrate interaction. The two contributions have, generally, different angular dependence, and always a different temperature dependence. This fact can explain recently observed surface transitions. By using a simple phenomenological model the tilt angle versus the temperature is analysed. The agreement with the experimental data is fairly good.

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