Max-Planck-Institut für Festkörperforschung, D-70506 Stuttgart, Germany
We study the condition for a Mott-Hubbard metal-insulator transition in a Hubbard model with the orbital degeneracy N. We find an increase by roughly a factor of sqrt{N} in the critical value of the Coulomb interaction U for which the transition takes place, explaining why A3C60 (A=K, Rb) are metals. We further calculate the many-body enhancement of the Pauli susceptibility. Taking this enhancement into account, we derive an estimate of the electron density of states.
in: Molecular nanostructures. Proceedings of the International Winterschool onElectronic Properties of Novel Materials. Singapore: World Scientific 229-234.
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