298 15 Liquid Crystals and Other Anisotropic Fluids
In thermal equilibrium, these derivatives are equal to zero. In connection with the
treatment of non-equilibrium phenomena, as considered in Chap. 17 , the governing
differential equations contain these derivatives of the potential function. The cou-
pling between the friction pressure tensor and the tetrahedral order parameter tensor
as discussed in [93] is described analogous to (15.58). Combined tetrahedral and
nematic order in liquid crystals and the consequences for chirality are discussed
in [99].