Renormalization Group Approach to the Coulomb Pseudopotential for C_{60}

TL;DR

This paper applies a numerical renormalization group method to analyze the Coulomb pseudopotential in C60, revealing significant screening effects and implications for superconductivity in fullerides.

Contribution

It introduces a renormalization group approach to compute the Coulomb pseudopotential in C60, highlighting the impact of intraball screening on superconductivity.

Findings

Large reduction of μ* due to intraball screening

μ* remains positive but small enough for superconductivity

Non-monotonic dependence of μ* on bare interaction strength

Abstract

A numerical renormalization group technique recently developed by one of us is used to analyse the Coulomb pseudopotential (${\mu^*}$) in ${{\rm C}_{60}}$ for a variety of bare potentials. We find a large reduction in ${\mu^*}$ due to intraball screening alone, leading to an interesting non-monotonic dependence of ${\mu^*}$ on the bare interaction strength. We find that ${\mu^*}$ is positive for physically reasonable bare parameters, but small enough to make the electron-phonon coupling a viable mechanism for superconductivity in alkali-doped fullerides. We end with some open problems.