Nonempirical study of superconductivity in alkali-doped fullerides based on density functional theory for superconductors

摘要

We apply the density functional theory for superconductors based on the local density approximation (LDA) to alkali-doped fullerides A_3C_(60) with a face-centered-cubic structure. We evaluate the superconducting transition temperature (T_c) from first principles considering the energy dependence of electron-phonon coupling, the mass renormalization, and the retardation effect. The calculated T_c = 7.5, 9.0, and 15.7 K for A = K, Rb, Cs are approximately 60% smaller than the experimentally observed values. Our results strongly suggest the necessity to go beyond the framework of the Migdal-Eliashberg theory based on the LDA.