M. Schüler, M. Rösner, T. O. Wehling, A. I. Lichtenstein, M. I. Katsnelson
We report on a method to approximate a generalized Hubbard model with nonlocal Coulomb interactions by an effective Hubbard model with on-site interactions U* only. The effective model is defined by the Peierls-Feynman-Bogoliubov variational principle. We find that the local part of the interaction U is reduced according to U* = U - V, where V is an average of nonlocal Coulomb interactions weighted according to derivatives of nonlocal charge correlation functions from the effective model. For the examples of graphene, silicene and benzene we show that the nonlocal Coulomb interaction can decrease the effective local interaction by more than a factor of 2.
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http://arxiv.org/abs/1302.1437
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