My model, it has three layers: a reduced model of the smectic transition in two dimensions

Abstract: My model, it has three layers, Three layers is nematic. And had it just two layers, it would be a smectic. We study a reduced model of the smectic transition in two dimensions where the particles occupy three equally spaced layers. The role of particle geometry comes in through the interactions between particles on the central layer and those above and below. The system is understood to be smectic when the central layer is empty, and nematic when all three are equally occupied. It is possible to compute the free energies of these states exactly. We find that the free energy of the nematic can only exceed that of the smectic if the particle tips are sufficiently wide, mirroring the fact that ellipsoids do not make a smectic but sphero-cylinders do.