Hamburg 2001 – wissenschaftliches Programm
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SYOF: Organische Festkörper
SYOF 5: Poster Session
SYOF 5.36: Poster
Dienstag, 27. März 2001, 17:00–19:00, Aula S3
Electronic band structure and intermolecular interaction in substituted thiophene polymorphs — •J. Widany1, G. Daminelli1, A. Di Carlo1, P. Lugli1, G. Jungnickel2, M. Elstner2, and T. Frauenheim2 — 1Dipartimento di Ingegneria Elettronica, Università di Roma II “Tor Vergata”, I-00133 Roma, Italy — 2Theoretische Physik, Fachbereich Physik, Universität-Gesamthochschule, D-33098 Paderborn, Germany
Total energy calculations based on a density-functional tight-binding scheme have been performed on polymorphic modifications of various thiophene crystals (β- tetra-methylsulphanyl)- α-quaterthiophene and (β- tetramethyl) -α-sexithiophene. The electronic band structures exhibit a quasi one dimensional interaction in the triclinic crystals, while the monoclinic modifications show no dispersion over the whole Brillouin zone. The main interaction mechanism can be described as a d−π wave function overlap between sulphur and carbon. The strong intermolecular interaction may induce an inter-chain excitation, responsible for the different optical properties of the polymorphs.