Dye-sensitized solar cells are promising for relatively high efficiency and low price compared to original thin-film model. The basic mechanism is that the dye molecules absorb light and are promoted into the excited electronic state. Thereafter the excited electron is transferred to TiO2. However, there are not many models that allow us to understand the molecular processes that occurs in dye-sensitized solar cells. Our research goal is to figure out the configuration of dye molecule (bi-isonicotinic acid) adsorbed on a TiO2 surface and to understand the molecular connection between the molecules and surface.