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EnglishWe propose a theoretical approach, within the framework of the composite operator method, to include the effects of finite cluster correlations into the self-energy of strongly correlated systems. The Hubbard model is analyzed as significant example. The self-energy is rewritten in terms of two-site composite-operator propagators, which are computed by means of a two-site approximation preserving relevant symmetries (e.g., particle–hole symmetry). The involved composite operators describe charge, spin and pair nearest-neighbor correlations and the excitations related to the induced exchange coupling (J=4t2/U). The procedure results in a very rich band structure going well beyond the results of the two-pole approximation.
| Titolo: | Effects of two-site correlations in the Hubbard model |
| Autori: | |
| Data di pubblicazione: | 2003 |
| Rivista: | |
| Abstract: | We propose a theoretical approach, within the framework of the composite operator method, to include the effects of finite cluster correlations into the self-energy of strongly correlated systems. The Hubbard model is analyzed as significant example. The self-energy is rewritten in terms of two-site composite-operator propagators, which are computed by means of a two-site approximation preserving relevant symmetries (e.g., particle–hole symmetry). The involved composite operators describe charge, spin and pair nearest-neighbor correlations and the excitations related to the induced exchange coupling (J=4t2/U). The procedure results in a very rich band structure going well beyond the results of the two-pole approximation. |
| Handle: | http://hdl.handle.net/11386/1064227 |
| Appare nelle tipologie: | 1.1.2 Articolo su rivista con ISSN |
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