Regensburg 2013 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 40: Poster Session Correlated Electrons
TT 40.77: Poster
Wednesday, March 13, 2013, 15:00–19:00, Poster D
A slave rotor approach to the dynamical screening of Coulomb interactions — •Igor Krivenko1,2, Silke Biermann2, and Alexander Lichtenstein1 — 1I. Institut für Theoretische Physik, Universität Hamburg, Jungiusstraße 9, 20355 Hamburg, Germany — 2Centre de Physique Théorique (CPHT), École Polytechnique, 91128 Palaiseau Cedex, France
We present a new theoretical approach to lattice and impurity models of strongly correlated electrons with the dynamically screened Coulomb interactions. The method is based on a slave rotors decoupling of the screened interaction and provides a consistent description of quantum impurities with both fermionic and bosonic bath. It is shown, that the simplest meaningful approximation within this method coincides with the dynamic atomic limit approximation (DALA). More refined approximations beyond DALA are constructible in a regular way using a saddle-point or perturbative treatment of the rotor degrees of freedom. The proposed method gives a computationally cheap way to apply existing quantum impurity solvers for unscreened static interactions to the cases of frequency-dependent interactions. It allows to calculate thermal Green's functions and higher-order correlation functions of the impurity models. These functions then can be used as building blocks of modern perturbative approaches to lattice models involving phonons, magnons and other bosonic excitations.