Dimerization and EnergyLevel Structures in Fullerene Tubules Investigated with an ElectronPhonon Model
Abstract
Possible dimerization patterns and electronic structures in fullerene tubules as the \piconjugated systems are studied with the extended SuSchrieffer Heeger model. We assume various lattice geometries, including helical and nonhelical tubules, and tubules with end caps. The model is solved for the halffilling case of \pielectrons. (1) When the undimerized systems do not have a gap, the Kekulé structures tend to occur. These structures are commensurate with the boundary condition in the direction perpendicular to the tubular axis. The energy gap is of the order of the room temperatures at most. Thus, the nearly metallic properties would be expected. (2) If the undimerized systems have a large gap (\sim 1eV), the most stable structures are the chainlike distortions where the direction of the arranged {\sl trans}polyacetylene chains is along almost the tubular axis. When we try to obtain the Kekulé structures, the mismatch of the boundary condition occurs and they are energetically unfavorable. The electronic structures are of semiconductors due to the large gap.
 Publication:

arXiv eprints
 Pub Date:
 August 1992
 arXiv:
 arXiv:condmat/9208019
 Bibcode:
 1992cond.mat..8019H
 Keywords:

 Condensed Matter
 EPrint:
 (proceedings of the International Conference on Science and Technology of Synthetic Metals 1992, to be published in "Synthetic Metals")