We have investigated the energy spectra, the electronic states and the localized modes of soliton by considering the effects of the square term of the electron-lattice interactions in the SSH model. Only the midgap state has been found, and the two bound states near the edge of the valence band and the conduction band obtained in the standard SSH models, disappear. The energy gap and the dimerization increase, but the total width of the energy band does not change. All five localized modes survive, and their localizations are strengthened and the frequencies are shifted.
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