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EnglishThe electronic states of the Hubbard model are investigated by use of the composite operator method. In addition to the Hubbard operators, two other operators related with two-site composite excitations are included in the basis. Within the present formulation, higher-order composite excitations are reduced to the chosen operatorial basis by means of a procedure preserving the particle-hole symmetry. The positive comparison with numerical simulations for the double occupancy indicates that such approximation improves over the two-pole approximation. © 2003 Elsevier B.V. All rights reserved.
| Titolo: | Effects of two-site composite excitations in the Hubbard model |
| Autori: | |
| Data di pubblicazione: | 2004 |
| Rivista: | |
| Abstract: | The electronic states of the Hubbard model are investigated by use of the composite operator method. In addition to the Hubbard operators, two other operators related with two-site composite excitations are included in the basis. Within the present formulation, higher-order composite excitations are reduced to the chosen operatorial basis by means of a procedure preserving the particle-hole symmetry. The positive comparison with numerical simulations for the double occupancy indicates that such approximation improves over the two-pole approximation. © 2003 Elsevier B.V. All rights reserved. |
| Handle: | http://hdl.handle.net/11386/1064265 |
| Appare nelle tipologie: | 1.1.2 Articolo su rivista con ISSN |
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