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TT: Tiefe Temperaturen
TT 11: Postersitzung II (Metall-Isolator-Überg
änge, Phasenüberg
änge in Quantensystemen, Theorie: Systeme korrelierter Elektronen)
TT 11.28: Poster
Tuesday, March 25, 2003, 14:30–19:00, P2c, P2d
Inhomogeneous Gutzwiller approximation with random phase fluctuations for the Hubbard model — •Götz Seibold1, Jose Lorenzana2, and Federico Becca3 — 1Lehrstuhl Theoretische Physik, BTU Cottbus, 03013 Cottbus, Germany — 2Universita di Roma ’La Sapienza’, P. Aldo Moro 2, 00185 Roma, Italy — 3International School for Advanced StudiesVia Beirut 4, 34013 Trieste, Italy,
We present a time-dependent Gutzwiller approximation (GA) for the Hubbard model which is analogous to the time-dependent Hartree-Fock (HF) method. The formalism, labelled GA+RPA, allows us to compute random-phase approximation-like (RPA) fluctuations on top of the Gutzwiller approximation (GA). No restrictions are imposed on the charge and spin configurations which makes the method suitable for the calculation of linear excitations around symmetry-broken solutions. Well-behaved sum rules are obeyed as in the Hartree-Fock (HF) plus RPA approach. Analytical results for a two-site model and numerical results for charge-charge and current-current dynamical correlation functions in one and two dimensions are compared with exact and HF+RPA results, supporting the much better performance of GA+RPA with respect to conventional HF+RPA theory.