Band structure calculations for some binary mixed alkali-metal doped C60

In this paper we present the three dimensional EHMO crystal orbital calculations for crystalline Li₂CsC₆₀, Na₂CsC₆₀, K₂CsC₆₀ and Rb₂CsC₆₀. For all these four dopants with a fcc structure, our calculated band structures and density of state unequivocally suggest a metallic conducting phase with each a set of three half-filled band across the Fermi level which is just located close to a peak of density of state. A monotonic relationship is found between our calculated Fermi-level density of state N and experimental transition temperature T_c which is in excellent agreement with some theoretical studies and experimental results. With our other calculation results, such as the overlap populations between A (where A represents an alkali-metal) and C₆₀ molecules, net atomic and orbital charges, crystal orbital vectors and various projected DOS, we could probably shed some light on the mechanism of the superconductivity for this new marvelous kind of materials from a chemical point of view.