Dielectric screening in doped Fullerides

TL;DR

This paper investigates whether dielectric screening via RPA accurately describes electron-electron interactions in alkali-doped Fullerides, which are strongly correlated systems near a Mott transition, using quantum Monte Carlo simulations.

Contribution

It provides a quantum Monte Carlo analysis to test the validity of RPA screening in strongly correlated alkali-doped Fullerides.

Findings

RPA may not be fully valid in these systems

Quantum Monte Carlo results show deviations from RPA predictions

Screening effects are crucial for understanding superconductivity in Fullerides

Abstract

For conventional superconductors the electron-electron interaction is strongly reduced by retardation effects, making the formation of Cooper pairs possible. In the alkali-doped Fullerides, however, there are no strong retardation effects. But dielectric screening can reduce the electron-electron interaction sufficiently, if we assume that the random-phase approximation (RPA) is valid. It is not clear, however, if this assumption holds, since the alkali-doped Fullerides are strongly correlated systems close to a Mott transition. To test the validity of the RPA for these systems we have calculated the screening of a test charge using quantum Monte Carlo.