Infrared Activity of Phonons around a Soliton in<i>trans</i>-(CH)_<i>x</i>and (CD)_<i>x</i>–The Origin of the New IR Active Modes–

Abstract

The dynamical conductivity due to phonons around a charged soliton is calculated, using Horovitz's three phonon band model for trans-polyacetylene. We find three weak i.r. modes in addition to the three intense ones which were known. The weak modes have their origins in the third localized mode which was found in the Takayama-Lin-Liu-Maki model. The vibration frequencies and relative optical intensities are calculated to give a good agreement with a recent photo-induced absorption experiment. This strongly indicates that there actually is the third localized mode.