Interaction and superconducting transition in alkali-doped C_(60)

The intermolecular interactions in alkali-doped C₆₀ solids, A_3-x-y A′_xA″_yC₆₀ (A, A′, A″ = alkali; x + y ? 3), have been calculated, and their correlations with the structures and the superconducting transition temperatures T_c have also been investigated. It is found that the variations of the lattice constants a₀ of A_{3-x- y} A′_x A″_y C₆₀ solids and the superconducting transition temperatures T_c can be satisfactorily explained from the viewpoint of interaction. It is shown that the relationship of T_c with interaction is much closer than that of T_c with lattice constant a₀, Therefore, we can say it is the physical factors such as interaction, other than the geometrical structure factors such as a₀, that should be reasonably taken as the primitive cause of the sudden change of superconductivity from pristine C₆₀ to its alkali-doped compounds and of the variation of T_c among superconductors of A_3-x-yA′_x A″ _y C₆₀