钾铷掺杂晶态C60的电子结构与超导性的研究

THE RELATION OF ELECTRONIC STRUCTURE AND SUPERCONDUCTIVITY OF CRYSTALLINGE DOPEND C_(60)

Three dimensional EHMO crystral orbital calculations for crystalline C60>K3C60 and Rb3C60,, are reported. The ground states of undoped solid C60 is found to be insulating with a direct energy gap of 1. 7eV at P. In contrast ,K3C60 and Rb3C60 forms a metallic conducting phase with a set of three half-filled bands crossing the Fermi level which isrfound to be located close to a peak of the density of state. The character of crystal orbitals near the Fermi level for both K3C60 and Rb3C60 is completely carbon-like. In both cases the K atoms and Rb atoms are almost fully ionized and C60 molecules could form a stable negtive charge state with three additional electrons. The projected DOS of K and Rb atoms near the Fermi-level and the overlap populations between K and Ca all neglectable.