Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 32: Correlated Electrons: Poster Session
TT 32.39: Poster
Donnerstag, 28. Februar 2008, 14:00–18:00, Poster B
Mott transition in one dimension: Benchmarking dynamical cluster approaches — •Matthias Balzer1, Werner Hanke1, and Michael Potthoff2 — 1Institut für Theoretische Physik und Astrophysik, Universität Würzburg — 2I. Institut für Theoretische Physik, Universität Hamburg
The variational cluster approach (VCA) is applied to the 1D Hubbard model at T=0 using clusters (chains) of up to ten sites with full diagonalization and the Lanczos method as cluster solver. Within the framework of the self-energy-functional theory (SFT), different cluster reference systems with and without bath degrees of freedom, in different topologies and with different sets of variational parameters are considered. Static and one-particle dynamical quantities are calculated for half-filling as a function of U as well as for fixed U as a function of the chemical potential to study the interaction- and filling-dependent metal-insulator (Mott) transition. We compare the VCA results with exact results available from the Bethe ansatz, with essentially exact dynamical DMRG data, with (cellular) dynamical mean-field theory and full diagonalization of isolated Hubbard chains. Several issues are discussed including convergence of the results with cluster size, the ability of cluster approaches to access the critical regime of the Mott transition and efficiency in the optimization of correlated-site vs. bath-site parameters. We also study the role of bath sites for the description of excitation properties and as charge reservoirs for the description of filling dependencies. The VCA turns out to be a computationally cheap method which is competitive with established cluster approaches.