Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 8: Superconductivity - Poster Session

TT 8.13: Poster

Montag, 26. März 2007, 14:00–17:45, Poster A

Time-dependent Gutzwiller theory of pair fluctuations in the attractive Hubbard model — •Falk Günther and Götz Seibold — BTU Cottbus, PO BOX 101344, 03013 Cottbus

The time-dependent Gutzwiller approximation (TDGA) is extended towards the inclusion of pair correlations.

The expansion of the charge-rotational invariant Gutzwiller energy functional around the saddle point allows the computation of dynamic correlation functions using the random-phase approximation (RPA). Unlike the BCS approach the interaction kernel in the TDGA mediates intersite pair scattering and also contains processes where pairs of electrons are created and annihilated on distant sites. It turns out that the TDGA can capture the crossover from weak to strong coupling in good agreement with Quantum Monte Carlo calculations in contrast to the BCS approximation.

As a further application we evaluate the excitations of the superconducting ground state. From the calculation of the instabilities in the particle-hole channel we construct the phase diagram for superconducting and charge order in two dimensional lattices.