Interchain interaction and fractionally charged solitons in a commensurate charge-density-wave system

We have studied the effect of interchain interaction on thermally excited solitons in a charge-density wave for a Peierls system of commensurability 3. In such a system solitons with charges $\pm \frac{2e}{3}$ are expected. It is shown that the interchain coupling in some cases will generate solitons with lower and higher charge than $\pm \frac{2e}{3}$. The effect of discreteness is taken into account and gives rise to chaotic deformed solitons as the interchain coupling increases. The model may be applied to tetrathiafulvalene tetracyanoquinodimethane (TTF-TCNQ) under 19-kbar pressure.