It is different from the case of conventional superconductors that the alkali-metal-doped fullerenes have wide-frequency-range phonon spectra whose high-and low-frequency phonon modes are, respectively, comparable to the Fermi energy EF and the zero-temperature gap △0. This property will lead to a modification to the theory of conventional strong coupling superconductivity. In this paper, by solving the Eliash-berg equations, the expressions of Tc and △0 are obtained. The results show that both the intermolecular low-frequency modes and the intramolecular highfrequency modes participate the electron-phonon interactions; Tc mainly arise from the high-frequency modes while △0's enhancement mainly arise from the low-frequency modes. So, the experimental results can be explained, especially, the large ratio of ２△0／ｋBＴc.
PACS:| 85.30.De | (Semiconductor-device characterization, design, and modeling) |
| 85.30.Kk | (Junction diodes) |
| 85.60.Jb | (Light-emitting devices) |
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