C. Papenfuss and W. Muschik
Constitutive Theory for two dimensional liquid crystals
Mol. Cryst. Liq. Cryst. 262, 1995, 473-484

Two dimensional liquid crystals are considered as mathematical surfaces of discontinuity of the bulk fields. The equations of motion for the relevant surface fields in the presence of electromagnetic fields are summarized. These are the mechanical balance equations, Maxwell's equations, and an equation of motion for the second order alignment tensor. The restrictions to constitutive functions implied by the second law of thermodynamics are discussed. The stress tensor can be calculated in the frame of this phenomenological theory. For the alignment production a statistical background is needed, what is very shortly outlined.