A study of the perfectly oriented Gay-Berne model of a nematic liquid crystal via perturbation theory and molecular dynamics

A perturbation theory for the Gay-Berne interaction potential has been developed and selected results are compared with those of molecular dynamics simulations for the same model. The perturbation method can be regarded as a generalization to oriented molecular fluids of the Weeks-Chandler-Andersen perturbation scheme. The properties of the soft repulsive reference system are related to a system of hard ellipsoids of revolution by the introduction of temperature and density dependent ellipsoidal axes. For the sake of simplicity and clarity both methods are applied to the perfectly ordered nematic phase, in which all particles are oriented in the same direction. Compressibility factors and structure factors were calculated via both routes for different temperatures and show remarkable agreement. Benefits and drawbacks of the two methods are discussed.