Landau–de Gennes theory

In physics, Landau–de Gennes theory describes the NI transition, i.e., phase transition between nematic liquid crystals and isotropic liquids, which is based on the classical Landau's theory and was developed by Pierre-Gilles de Gennes in 1969. The phenomonological theory uses the ${\displaystyle \mathbf {Q} }$ tensor as an order parameter in expanding the free energy density.