LOCALIZED VIBRATIONAL-MODES AROUND SOLITONS IN COUPLED TRANSPOLYACETYLENE CHAINS

The effects of interchain coupling have been studied on the localized vibrational modes around a soliton in doped and photoexcited samples o f trans-(CH)(x) by using an extension of the SSH model in which two ne ighboring chains modeled individually by SSH Hamiltonian and coupled b y an interchain electronic transfer term are considered. The electroni c pinning: is also included within this model. The localized modes obt ained in the SSH model are split and their frequencies are shifted aft er turning on the interchain coupling. Furthermore, our result can acc ount for the three strong infrared lines at 900, 1260 and 1370 cm(-1) along with a weaker peak at 1150 cm(-1) in the optical absorption spec tra of lightly doped samples.