Electronic band structure and intermolecular interaction in substituted thiophene polymorphs - art. no. 233204

Total energy calculations based on a density-functional tight-binding schem e have been performed on polymorphic modifications of various thiophene cry stals. The electronic band structures exhibit a quasi-one-dimensional inter action in the triclinic crystals, while the monoclinic modifications show n o dispersion over the whole Brillouin zone. The main interaction mechanism can be described as a d-pi wave function overlap between sulfur and carbon. The strong intermolecular interaction may induce an interchain excitation, responsible for the different optical properties of the polymorphs.