Vibronic model Hamiltonian for the study of the near-IR-visible optical properties of [(NH3)(5)Ru-(4,4 '-bipyridine)-Ru(NH3)(5)](m+) (m=4, 5): Chargelocalization and electroabsorption spectra

A vibronic model Hamiltonian suitable for the study of the optical properti es in the near-IR-visible of partially localized systems is presented and d iscussed. The problem of how to deal with localization in a symmetric speci es is examined in view of understanding the origin of the observed Stark sp ectra. It is shown that a weak perturbation that breaks the symmetry of the Hamiltonian, such as that due to interaction with the solvent, allows char ge localization in the ground state, as well as provides for a good predict ion of the observed Stark spectra.