THE EFFECT OF THE ELECTRON-PHONON COUPLING ON SINGLE-LAYER BACKYONIONS

The electronic and the geometric structures of the metallic and the se miconducting carbon onions are studied. Taking into account the electr on-phonon coupling, both classes of onions are found to suffer Peierls instability. Also, the C-C bonds are dimerized, the binding energies are increased, and the energy gaps are enlarged. The symmetries of the geometric and the electronic structures of metallic onions are reduce d, while those of semiconducting onions are not. The distortions of th e structures decrease as the number of carbon atoms increases. The dim erization patterns of these onions are also presented.