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Title: The effects of the next-nearest-neighbour density-density interaction in the atomic limit of the extended Hubbard model
Authors: Kapcia, Konrad
Robaszkiewicz, Stanisław
Keywords: charge orderings
phase separations
extended Hubbard model
atomic limit
Issue Date: 16-Mar-2011
Publisher: IOP Publishing Ltd., Temple Circus, Temple Way, Bristol BS1 6BE, England
Citation: Journal of Physics: Condensed Matter, Vol. 23, No. 10, 105601 (1-12) (2011)
Abstract: We have studied the extended Hubbard model in the atomic limit. The Hamiltonian analyzed consists of the effective on-site interaction U and the intersite density-density interactions Wij (both: nearest-neighbour and next-nearest-neighbour). The model can be considered as a simple effective model of charge ordered insulators. The phase diagrams and thermodynamic properties of this system have been determined within the variational approach, which treats the on-site interaction term exactly and the intersite interactions within the mean-field approximation. Our investigation of the general case taking into account for the first time the effects of longer-ranged density-density interaction (repulsive and attractive) as well as possible phase separations shows that, depending on the values of the interaction parameters and the electron concentration, the system can exhibit not only several homogeneous charge ordered (CO) phases, but also various phase separated states (CO-CO and CO-nonordered). One finds that the model considered exhibits very interesting multicritical behaviours and features, including among others bicritical, tricritical, critical-end and isolated critical points.
Description: This is an author-created, un-copyedited version of an article accepted for publication in Journal of Physics: Condensed Matter. IOP Publishing Ltd. is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at
DOI: 10.1088/0953-8984/23/10/105601
ISSN: 0953-8984
Appears in Collections:Artykuły naukowe (WF)

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