OPTICAL SUM RULE IN STRONGLY CORRELATED SYSTEMS
Kuchinskii E.Z., Kuleeva N.A., Nekrasov I.A., Sadovskii M.V.

Received: March 27, 2008

PACS: 74.25.Gz, 71.10.Fd, 71.10.Hf, 71.27.+a, 71.30.+h, 74.72.-h

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We discuss the problem of a possible ``violation'' of the optical sum rule in the normal (nonsuperconducting) state of strongly correlated electronic systems, using our recently proposed DMFT+Σ approach applied to two typical models: the ``hot spot'' model of the pseudogap state and disordered Anderson-Hubbard model. We explicitly demonstrate that the general Kubo single-band sum rule is satisfied for both models. But the optical integral itself is in general dependent on temperature and characteristic parameters, such as the pseudogap width, correlation strength, and disorder scattering, leading to an effective ``violation'' of the optical sum rule, which may be observed in the experiments.