Optical Studies of Halogen-Bridged Mixed-Valent Metal Complexes

Abstract

A brief review of theoretical studies on the optical properties of halogen-bridged mixed-valent metal complexes is given, with special emphasis on the following two topics. The first topic is the various optical properties of charge-transfer excitons. In order to show them, we introduce a theory of the various optical spectra which are obtained in charge- density-wave ground state. In that theory, two important effects beyond the mean-field theory are taken into account: the electron-hole correlation on the metal atoms and the classical fluctuation of the halogen-sublattice coordinates. It is found that the spectral shapes both of the linear absorption and of that in an electric field, i.e., the electroabsorption agree well with the experimental results