Luckhurst–Romano model of thermotropic biaxial nematic phase

Recent experiments show that the long looked for thermotropic biaxial nematic phase is finally stabilized in a low mass liquid crystalline system. Inspired by this experimental observation we concentrate on some theoretical issues concerned with this phase. In particular we show that the simplest Lebwohl–Lasher biaxial model, as introduced by Luckhurst and Romano, is consistent with the minimal coupling Landau–de Gennes phenomenological approach. The model shows a rich spectrum of possibilities, in particular a direct isotropic–biaxial nematic phase transition. A possible bridge between molecular and phenomenological approaches, in particular an interpretation of the alignment tensor, is discussed.