Improvement of C$_{60}$'s calculated electron-phonon coupling using hybrid functional

ORAL

Abstract

Superconductivity in doped C$_{60}$ crystals is generally admitted to be phonon mediated. However, the electron-phonon coupling calculated within density functional theory do not agree with measured values, in contrast to others phonon related properties. This discrepancy hasn't been understood yet. Up to now, only calculations using the local density approximation for the exchange-correlation functional (LDA) were performed. In this study, we demonstrate that using exact-exchange functionals increases the calculated couplings, bringing it closer to experiment, while others properties, such as geometry and phonon frequencies, are little affected. We investigate how such an improvement is possible while little change is seen on more commonly calculated properties.

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Authors

  • Jonathan Laflamme Janssen

    D\'epartement de physique and Regroupement qu\'eb\'ecois sur les mat\'eriaux de pointe (RQMP), Universit\'e de Montr\'eal, Canada

  • Michel C\^ot\'e

    Departement de physique et Regroupement quebecois sur les materiaux de pointe (RQMP), Universite de Montreal, Canada, D\'epartement de physique and Regroupement qu\'eb\'ecois sur les mat\'eriaux de pointe (RQMP), Universit\'e de Montr\'eal, Canada

  • Steven G. Louie

    The department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory, UC Berkeley, Lawrence Berkeley National Labratory, University of California Berkeley, Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, Department of Physics, University of California, Berkeley and Lawrence Berkeley National Laboratory, Department of Physics, University of California at Berkeley and Materials Sciences Division of Lawrence Berkeley National Laboratory, University of California, Berkeley, University of California at Berkeley and Lawrence Berkeley National Lab

  • Marvin L. Cohen

    The department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory, UC Berkeley, Lawrence Berkeley National Labratory, University of California Berkeley, Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, Department of Physics, University of California, Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory, Department of Physics, University of California at Berkeley and Materials Sciences Division of Lawrence Berkeley National Laboratory, Physics Dept, UC Berkeley, University of California, Berkeley and MSD, Lawrence Berkeley National Laboratory