Drude Weight of Three-Band Hubbard Model for A_xC_<60> Compounds(Condensed matter: electronic structure and electrical, magnetic, and optical properties)

概要

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By numerical calculation for the three-band Hubbard model, we investigate the role of the difference between interorbital and intraorbital interactions in alkali-metal-doped C_<60>, A_xC_<60> (A=K, Rb, etc.). In order to explain the observed optical conductivity, the consideration of the difference is essential. In fact, A_2C_<60> and A_4C_<60> lose the metallic conductivity such as Drude weight with decreasing intraorbital interaction under the condition of constant interorbital interaction: In spite of the decrease in total correlations, the metallic behavior disappears. In contrast, A_3C_<60> retains its metallic behavior. These reasons are made clear on the basis of the change in the electronic configurations in the ground states.
2008-04-15