POLARON EXCITATION IN TRANSPOLYACETYLENE - EFFECTS OF THE 2ND-NEARESTNEIGHBOR HOPPING INTERACTIONS

We have studied the energy spectra of polaron and the localized vibrat ional modes around a polaron in the weakly coupled electron-phonon sys tems by using an extension of SSH model that includes the second-neare st neighbor hopping interactions. The results show that (1) The electr on-hole symmetry of the energy band structure is broken and the energy gap 2 Delta is slightly increased. (2) The number of localized electr onic states and their location are changed as in the soliton case. (3) For a negative polaron, eight localized modes have been found, compar ed with seven in the previous results. (4) The energy spectra of polar on and the localized modes are related to the types of polarons by tur ning on the second-neighbor hopping interactions.