On the role of spherical symmetry in the Maier-Saupe theory

The Maier-Saupe theory of the isotropic-nematic phase transition contains two crucial elements. First the orientational order in the nematic phase is attributed to the anisotropic part of the Van der Waals forces between the anisotropic molecules. In addition, in applying a mean-field approximation spherical symmetry around a central molecule is assumed. In this paper the consequences of this contradiction are investigated within the context of the theory. It is shown that relatively small deviations from spherical symmetry already destroy the orientational order. Hence the success of the Maier-Saupe potential is due to other reasons outside the original theory.