Coulomb pseudopotential, screening and superconductivity inC60

We estimate the Coulomb pseudopotential ${\mathrm{\mu }}^{\mathrm{*}}$ for a model of undoped ${\mathrm{C}}_{60}$, renormalizing away all subbands but the ${\mathit{t}}_{1\mathit{u}}$ conduction band by summing ladder diagrams in the screened interaction. The renormalization of ${\mathrm{\mu }}^{\mathrm{*}}$ is small. For doped ${\mathrm{C}}_{60}$ the screened U is calculated. A very efficient metallic screening is found for the intraband U, but not for the interband U, suggesting a large renormalization of ${\mathrm{\mu }}^{\mathrm{*}}$ within a ladder diagram approach. Exact results for a two-band model suggest, however, that the ladder diagrams strongly overestimate the renormalization.