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TT: Fachverband Tiefe Temperaturen
TT 45: Correlated Electrons: Poster Session
TT 45.109: Poster
Donnerstag, 29. März 2012, 15:00–19:00, Poster B
Instability of a repulsive Bose gas near the BEC transition — •Michael Maennel1, Klaus Morawetz1,2, and Pavel Lipavsky3,4 — 1Department Physical Engineering, Münster University of Applied Science, 48565 Steinfurt, Germany — 2International Institute of Physics, Universidade Federal do Rio grande do Norte, 59.072-970 Natal-RN, Brazil — 3Institute of Physics, Academy of Sciences, Cukrovarnická 10, 16253 Prague 6, Czech Republic — 4Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 12116 Prague 2, Czech Republic
We investigate a Bose gas with finite-range interaction using a scheme to eliminate self-interaction in the T-matrix approximation. In this way the corrected T-matrix becomes suitable to calculate properties below the critical temperature, without the use of anomalous functions. In the vicinity of the onset of Bose-Einstein condensation (BEC) chemical potential and pressure show a van-der-Waals like behavior indicating a first-order phase transition although there is no long-range attraction. Furthermore for sufficiently strong interaction the equation of state becomes multivalued near the BEC transition. For a Hatree-Fock or Hartree-Fock-Bogoliubov approximation such a multivalued region can be avoided by a Maxwell construction. However, for the T-matrix approximation there remains a multivalued region even after a Maxwell construction.