Process-chain approach to the Bose-Hubbard model: Ground-state properties and phase diagram
- Institut fuer Physik, Carl von Ossietzky Universitaet, D-26111 Oldenburg (Germany)
We carry out a perturbative analysis, of high order in the tunneling parameter, of the ground state of the homogeneous Bose-Hubbard model in the Mott insulator phase. This is made possible by a diagrammatic process-chain approach, derived from Kato's representation of the many-body perturbation series, which can be implemented numerically in a straightforward manner. We compute ground-state energies, atom-atom correlation functions, density-density correlations, and occupation number fluctuations, for one-, two-, and three-dimensional lattices with arbitrary integer filling. A phenomenological scaling behavior is found which renders the data almost independent of the filling factor. In addition, the process-chain approach is employed for calculating the boundary between the Mott insulator phase and the superfluid phase with high accuracy. We also consider systems with dimensionalities d>3, thus monitoring the approach to the mean-field limit. The versatility of the method suggests further applications to other systems which are less well understood.
- OSTI ID:
- 21287029
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 79, Issue 22; Other Information: DOI: 10.1103/PhysRevB.79.224515; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ATOM-ATOM COLLISIONS
ATOMS
COMPUTERIZED SIMULATION
CORRELATION FUNCTIONS
CORRELATIONS
DISTURBANCES
FLUCTUATIONS
GROUND STATES
HUBBARD MODEL
MANY-BODY PROBLEM
MEAN-FIELD THEORY
OCCUPATION NUMBER
PERTURBATION THEORY
PHASE DIAGRAMS
SCALING
SUPERFLUIDITY
THREE-DIMENSIONAL CALCULATIONS
TUNNEL EFFECT