Dimerization problem in conjugated polymers

Applying the self-consistent solitonic approach [1] to the extended Peierls -Hubbard model on odd rings, the interplay of el-el interactions U, V, vari ous off-diagonal interactions, and external dimerization for the dimerizati on amplitude is studied by exact diagonalizations in the adiabatic limit. T he applicability of an effective spin-Peierls Hamiltonian in the intermedia te correlation regime U similar to 3t typical for conjugated polymers and a ll approximate analytical solution based on the Bethe-ansatz solution for t he spin velocity and the continuum model solution for the spin-Peierls prob lem are discussed.