2005/11/30 by W. Koller, W Koller, N. Dupuis +1 · 2 citations
Materials Science · Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Iron-based superconductors research #Physics of Superconductivity and Magnetism #cond-mat.other #cond-mat.stat-mech
paper · pdf · doi:10.1088/0953-8984/18/41/019
published as J. Phys.: Condens. Matter 18 (2006) 9525-9540 · v1) 10 pages, 6 figures. v2) Final version as published
openalex publication_date 2006/09/29 · arxiv created 2006/10/02 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/30
We discuss the application of the variational cluster perturbation theory (VCPT) to the Mott-insulator-to-superfluid transition in the Bose–Hubbard model. We show how the VCPT can be formulated in such a way that it gives a translation invariant excitation spectrum—free of spurious gaps—despite the fact that it formally breaks translation invariance. The phase diagram and the single-particle Green function in the insulating phase are obtained for one-dimensional systems. When the chemical potential of the cluster is taken as a variational parameter, the VCPT reproduces the dimensional dependence of the phase diagram even for one-site clusters. We find a good quantitative agreement with the results of the density-matrix renormalization group when the number of sites in the cluster becomes of order 10. The extension of the method to the superfluid phase is discussed.