| Doublon-Holon Binding Effects on Mott Transitions in Two-Dimensional Bose Hubbard Model (2007) | |||||||||
Abstract | |||||||||
| A mechanism of Mott transitions in a Bose Hubbard model on a square lattice is studied, using a variational Monte Carlo method. Besides an onsite correlation factor, we introduce a four-body doublon-holon factor into the trial state, which considerably improves the variational energy and can appropriately describe a superfluid-insulator transition. Its essense consists in binding (and unbinding) of a doublon to a holon in a finite short range, identical with the cases of fermions. The features of this transition are qualitatively different from those of Brinkman-Rice-type transitions.. Comment: 5 pages, 6 figures, proceedings of SNS2007 | |||||||||
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