OPTICAL-PROPERTIES OF LINEAR MIXED-VALENCE COORDINATION-COMPOUNDS BY 2-BAND HUBBARD HAMILTONIAN

We have investigated the optical conductivity spectra of M(LM)n linear complexes, as well as their periodic (ring) counterparts, whose constituent elements are transition metal ions (M), bridged by ligand species (L), through a two-band Hubbard Hamiltonian modified to include the effect of orbital expansion/contraction upon electron/hole occupation. It is shown that interesting conductive properties appear by doping, i.e. by varying the oxidation state of a fraction of the Ms. In the specific case of the Creutz-Taube ions ((Ru-L-Ru)m+; m=4, 5, 6) we were able to reproduce the low-frequency behaviour observed experimentally.