Extended self-energy functional approach for strongly correlated lattice bosons in the superfluid phase

Journal Article · Fri Jul 01 00:00:00 EDT 2011 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.84.014535· OSTI ID:21596821

Arrigoni, Enrico; Knap, Michael; Linden, Wolfgang von der ^[1]

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1. Institute of Theoretical and Computational Physics, Graz University of Technology, A-8010 Graz (Austria)

Among the various numerical techniques to study the physics of strongly correlated quantum many-body systems, the self-energy functional approach (SFA) has become increasingly important. In its previous form, however, SFA is not applicable to Bose-Einstein condensation or superfluidity. In this paper, we show how to overcome this shortcoming. To this end, we identify an appropriate quantity, which we term D, that represents the correlation correction of the condensate order parameter, as it does the self-energy for Green's function. An appropriate functional is derived, which is stationary at the exact physical realization of D and of the self-energy. Its derivation is based on a functional-integral representation of the grand potential followed by an appropriate sequence of Legendre transformations. The approach is not perturbative and, therefore, applicable to a wide range of models with local interactions. We show that the variational cluster approach based on the extended self-energy functional is equivalent to the ''pseudoparticle'' approach proposed in Phys. Rev. B 83, 134507 (2011). We present results for the superfluid density in the two-dimensional Bose-Hubbard model, which shows a remarkable agreement with those of quantum-Monte-Carlo calculations.

• OSTI ID: 21596821
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 84, Issue 1; Other Information: DOI: 10.1103/PhysRevB.84.014535; (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BOSE-EINSTEIN CONDENSATION
BOSONS
COMPUTERIZED SIMULATION
CONDENSATES
CORRELATIONS
GREEN FUNCTION
HUBBARD MODEL
INTERACTIONS
MONTE CARLO METHOD
ORDER PARAMETERS
SELF-ENERGY
SUPERFLUIDITY
TRANSFORMATIONS
TWO-DIMENSIONAL CALCULATIONS
VARIATIONAL METHODS
CALCULATION METHODS
CRYSTAL MODELS
DIMENSIONLESS NUMBERS
ENERGY
FUNCTIONS
MATHEMATICAL MODELS
SIMULATION