NEW ENERGY-SPECTRA STRUCTURE OF POLARON IN TRANSPOLYACETYLENE

In the weakly coupled electron-phonon systems, the existing theory poi nted out that the energy spectra of polaron include four electronic bo und states. Our work shows that, due to the non-nearest neighbor hoppi ng interactions, the electron-hole symmetry of the energy band structu re implied by SSH model is broken, and the numbers of the bound electr onic states are changed. For a negative charged polaron, one new bound state is found near the bottom of conduction band, and the original t wo bound states below the bottom of the valence band and above the top of the conduction band disappear. For a positive charged polaron, fiv e bound states have been found: one of them is an additional bound sta te at the top of the conduction band, the others are just the states f ound in the SSH model. Besides, the energy gap 2 Delta is slightly shi fted by turning on the long-range hopping interactions.