The paper considers the possibility of forming a Bose-Einstein condensate (BEC) of excitons in a model non-ideal lattice of a molecular crystal. The spectrum of the corresponding exciton excitations is analyzed. Within the framework of the virtual crystal approximation, a numerical simulation of the potential dependence on the concentration of structural defects was performed, and on this basis, the features of the appearance of exciton condensate in a non-ideal system were studied. It is shown under what conditions the appearance of light and dark excitons BEC is possible.

The propagation of a switching wave (kink) in two-component crystals during plastic torsion strain has been considered. The phenomenological Landau theory with consideration of Lifshitz invariants was used. A numerical simulation of the shape of the kink that occurs under various temperatures has been performed.