KONDO RESONANCE AND LOG-T CONDUCTIVITY IN HIGHLY CONDUCTING TRANSPOLYACETYLENE

The density of states of a U-impurity in a chain of trans-polyacetylene is calculated as a function of the atomic impurity level and the hybridization energy. A residual gap in the density of states of the conduction band is included. It is shown that a Kondo-like resonance exists at the top of the gap and that a log T behavior should occur in the resistivity of the sample, as experiments have revealed. We demonstrate that in order to observe the resonance, the gap must be smaller than the Kondo temperature in the gapless system.