Mott transition in degenerate Hubbard models: application to doped fullerenes.

Gunnarsson O., Koch E., Martin R. M.

Max-Planck-Inst. Festkoerperforschung, Stuttgart, D-70506, Germany

The Mott-Hubbard transition is studied for a Hubbard model with orbital degeneracy N, using a diffusion Monte Carlo method. Based on general arguments, the authors conjecture that the Mott-Hubbard transition takes place for U/W .apprx. .sqroot.N, where U is the Coulomb interaction and W is the bandwidth. This is supported by exact-diagonalization and Monte Carlo calcns. Realistic parameters for the doped fullerenes lead to the conclusions that stoichiometric A3C60 (A = K, Rb) are near the Mott-Hubbard transition, in a correlated metallic state.

Physical Review B, 54 R11026-R11029, 1996.

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