| We have developed a diagrammatic scheme that allows us to evaluate expectation values for Gutzwiller wave functions in one, two and three dimensions. Unlike an alternative variational Monte-Carlo calculation, our approach does not suffer from serious finite-size errors and and it is, numerically, rather cheap. Therefore, a study of multi-band models is feasible. In our presentation we shall give a thorough introduction into our new approach and show first results for the single-band Hubbard model in one and two dimensions. |
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