Spinodal curve of a three-component molecular system

We consider a lattice model for three-component systems in which the lattice bonds are covered by molecules of type AA, BB, and AB, and the only interactions are between the molecular ends of a common lattice site. The model is equivalent to the standard Ising model, and the coexistence curves for different lattices and/or some specific form of the interactions have been previously investigated. We derive the spinodal curve of the three-component model on the honeycomb lattice based on the mean-field and Bethe-lattice results of the equivalent Ising model. The spinodal and the coexistence curves of the ternary solution are drawn at different values of the reduced temperature, the only parameter of the model. The particular case of a two-component system is also illustrated.