Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 6: Postersession Correlated Electrons: (General) Theory, Low-Dimensional Systems, Kondo Physics, Heavy Fermions, Quantum-Critical Phenomena
TT 6.7: Poster
Montag, 23. März 2009, 13:00–16:45, P1A
CDMFT and DCA with Lanczos solver — •giorgio sangiovanni1, erik koch2, and olle gunnarsson3 — 1Vienna University of Technology — 2Forschungszentrum Jülich — 3Max-Planck Institut Stuttgart
Quantum cluster methods are among the most powerful tools to study strongly correlated systems. While a huge variety of impurity-solver are available nowadays for single-site Dynamical Mean Field Theory, for Cellular Dynamical Mean Field Theory (CDMFT) and Dynamical Cluster Approximation (DCA) only Quantum Monte Carlo-based solvers are usually employed. Exact Diagonalization has been hitherto used only for extremely small clusters. We introduce Hamiltonian-based solver using Lanczos at T=0 exploiting the cluster point symmetry. This implies symmetries of the hybridization, which can substantially reduce the number of independent parameters to fit the bath Green function. We review these symmetries and derive general sum-rules for the hybridizations, which (i) allow to check the quality of a fit using a finite set of bath sites and (ii) imply what hybridizations vanish. Such rationalization of the Lanczos solver is a necessary step towards a more efficient algorithm which may eventually allow us to treat larger systems.