Finite-density Onsager-type theory for the isotropic-nematic transition of hard ellipsoids

Abstract

We propose a simple density-functional theory for the isotropic-nematic transition of a system of hard ellipsoids which yields results in fair agreement with the computer simulation studies and which reduces exactly to Onsager's theory in the limit of infinitely dilute systems of infinitely long ellipsoids. When the free energy is expanded with respect to the Maier-Saupe quadrupole order parameter an explicit Landau theory is produced which yields good results for small nonsphericities. The theory also predicts a Lindemann rule for orientational freezing.