Theory for Special Shape of Optical Absorption in Halogen-Bridged Mixed-Valent Metal Complexes

概要

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Spectral shapes of optical absorptions in the charge density wave states of halogen-bridged mixed-valent metal complexes are theoretically determined for the first time,using a one-dimensional extended Peierls-Hubbard model. Two important effectsbeyond the mean field theory are taken into account; the electron-hole (e-h) correla-tion on the metal atoms, and the classical fluctuation of the halogen sublattice coor-dinates. It is shown that the exciton strongly affects the spectral shape of the chargetransfer (CT) band. When the e-h binding is weak, the CT band is the mixture of theexciton absorption and the interband ones. When it is strong, on the other hand, theexciton dominates over all the CT band and, consequently, its higher energy sidebecomes very close to a Lorentzian. From the comparison with experimental data, itis concluded that platinum complexes correspond to strong binding cases. The in-tragap absorptions associated with nonlinear excitations such as solitons andpolarons are also studied in a strong binding regime.
社団法人日本物理学会の論文
1992-04-15