We study how the electron hopping reduces the Mott-Hubbard band gap in the limit of a large Coulomb interaction U and as a function of the orbital degeneracy N. The results support the conclusion that the hopping contribution grows as roughly \sqrt{N}W, where W is the one-particle band width, but in certain models a crossover to a \sim NW behavior is found for a sufficiently large N.
@article{arxiv.cond-mat/9701151,
title = {Mott-Hubbard insulators for systems with orbital degeneracy},
author = {Olle Gunnarsson and Erik Koch and Richard M. Martin},
journal= {arXiv preprint arXiv:cond-mat/9701151},
year = {2009}
}
Comments
7 pages, revtex, 6 figures more information at http://www.mpi-stuttgart.mpg.de/dokumente/andersen/fullerene/