Ordering and Distortion at the Nematic-Isotropic Fluid Interface

A simple phenomenological theory is presented for the dependence of the surface tension γ at the nematic-vapor interface in terms of the order parameter Qij. Account is taken of the observations that γ is often discontinuous at the nematic-isotropic transition, and that there is usually a preferred orientation at the free surface. The derived γ is anisotropic and depends on the angle between the normal to the surface. The derived γ is anisotropic and depends on the angle between the normal to the sufrace and the orientation at the surface. Two simple examples of possible distortions in the surface and the orientation at the surface. Two simple examples of possible distortions in the orientation are considered. Since γ depends upon the scalar order parameter S it is possible to have an excess order near the surface. The value of the excess order and its decay depth are calculated.