Variational cluster approach for strongly correlated lattice bosons in the superfluid phase
- Institute of Theoretical and Computational Physics, Graz University of Technology, A-8010 Graz (Austria)
We extend the variational cluster approach to deal with strongly correlated lattice bosons in the superfluid phase. To this end, we reformulate the approach within a pseudoparticle formalism, whereby cluster excitations are described by particlelike excitations. The approximation amounts to solving a multicomponent noninteracting bosonic system by means of a multimode Bogoliubov approximation. A source-and-drain term is introduced in order to break U(1) symmetry at the cluster level. We provide an expression for the grand potential, the single-particle normal and anomalous Green's functions, the condensate density, and other static quantities. As a first nontrivial application of the method we choose the two-dimensional Bose-Hubbard model and evaluate results in both the Mott and the superfluid phases. Our results show an excellent agreement with quantum Monte Carlo calculations.
- OSTI ID:
- 21538271
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 83, Issue 13; Other Information: DOI: 10.1103/PhysRevB.83.134507; (c) 2011 American Institute of Physics; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
APPROXIMATIONS
COMPUTERIZED SIMULATION
CONDENSATES
DENSITY
EXCITATION
GREEN FUNCTION
HUBBARD MODEL
MONTE CARLO METHOD
SUPERFLUIDITY
TWO-DIMENSIONAL CALCULATIONS
U-1 GROUPS
VARIATIONAL METHODS
CALCULATION METHODS
CRYSTAL MODELS
ENERGY-LEVEL TRANSITIONS
FUNCTIONS
LIE GROUPS
MATHEMATICAL MODELS
PHYSICAL PROPERTIES
SIMULATION
SYMMETRY GROUPS
U GROUPS