Comparison of the Multi-Band Hubbard and Heisenberg Models on Small Finite Clusters |
| J. Matysiak and R. Lemański
Institute of Low Temperature and Structure Research, Polish Academy of Science, Okólna 2, 50-422 Wrocław, Poland |
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| We perform: exact numeric calculations for a few versions of the two-orbital Hubbard model on the four site cluster. We show that the conventional spin 1 Heisenberg Hamiltonian can be obtained in the strong coupling limit, but only for some versions of the two-orbital Hubbard model. Then we propose a modified version: of the Heisenberg Hamiltonian, that we call the two-orbital Heisenberg model, which is relevant in those cases, where the conventional spin 1 Heisenberg model fails. |
DOI: 10.12693/APhysPolA.133.405 PACS numbers: 31.15.vq, 75.10.Jm, 75.10.Pq |