Andersen Group El.-Phon. QMC C60 GW Resistivity saturation


The static screening plays an important role in the estimate of the Coulomb pseudopotential mu*. The screening was first calculated within the random phase approximation (RPA) for a model with a long-ranged Coulomb interaction. The screening was found to be very efficient within the RPA, and it leads to a large reduction of mu*. In view of the strong correlation effects in these systems, the accuracy of RPA may seem very questionable. For this reason, the static screening has been studied in a lattice Quantum Monte Carlo method for a Hubbard-like model of A3C60 ( Phys. Rev. Lett. , 83 , 620 (1999) ). RPA was found to be surprisingly accurate for values of the Coulomb interaction U which correspond to a metal. For values of U close to a Mott transition the screening becomes less efficient than predicted by RPA and for a Mott insulator RPA is qualitatively wrong.

Max-Planck Institut für Festkörperforschung
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Andersen Group Max-Planck-Institut für Festkörperforschung
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