Optical conductivity for a dimer in the dynamic Hubbard model

The dynamic Hubbard model represents the physics of a multiband Hubbard model by using a pseudospin degree of freedom to dynamically modify the on-site Coulomb interaction. Here we use a dimer system to obtain analytical results for this model. The spectral function and the optical conductivity are calculated analytically for any number of electrons, and the distribution of optical spectral weight is analyzed in great detail. The impact of polaronlike effects due to overlaps between pseudospin states on the optical spectral weight distribution is derived analytically. Our conclusions support results obtained previously with different models and techniques: holes are less mobile than electrons.