An excitonic method based on PPP Hamiltonian: application to the dimerization of polyenes

Starting from the Pariser-Parr-Pople Hamiltonian, we have proposed an effective Hamiltonian based on a local description of a conjugated polymer in terms of monomers. The model is adapted to the description of the ground and low energy excited states. It is here applied to treat the problem of dimerization of trans-polyacetylene and its evolution when the polyene size decreases.