Derization 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, various off-diagonal interactions, and external dimerization for the dimerization amplitude is studied by exact diagonalizations in the adiabatic limit. The applicability of an effective spin-Peierls Hamiltonian in the intermediate correlation regime U ~ 3t typical for conjugated polymers and an approximate analytical solution based on the Bethe-ansatz solution for the spin velocity and the continuum model solution for the spin-Peierls problem are discussed.