Assistant Professor Ohmura Shu and Professor Takahashi Akira of the Nagoya Institute of Technology and others have developed a charge model to describe photo-excited states of one-dimensional Mott insulators under the JST Strategic Basic Research Programs. They have also succeeded in constructing a many-body Wannier function as the localized basis state of the photo-excited states and calculating large-system, optical conductivity spectra that can be compared with experimental results.