Regensburg 2013 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 51: Correlated Electrons: General Theory 1

TT 51.6: Vortrag

Donnerstag, 14. März 2013, 10:45–11:00, H6

Quasi continuous-time impurity solver for dynamical mean-field theory with linear scaling in the inverse temperature — •Daniel Rost¹, Fakher Assaad², and Nils Blümer¹ — ¹Institute of Physics, Johannes Gutenberg-University, Mainz — ²Institute of Theoretical Physics and Astrophysics, University of Würzburg

Diagrammatic quantum Monte Carlo impurity solvers (CT-QMC) provide numerically exact solutions for dynamical mean-field theory (DMFT), at a computational cost that scales cubically with the inverse temperature β. In contrast, a recently proposed approach [1], based on a hamiltonian representation of the bath Green function and the BSS quantum Monte Carlo algorithm [2], scales linearly with β, but introduces a bias due to Trotter discretization. We present an algorithm, based on multigrid extrapolations of Green functions, that combines the advantages of both methods: (i) it retains the superior linear scaling of BSS and (ii) is free of significant Trotter errors. The accuracy of this quasi continuous-time method is established for the metal-insulator transition in the 1-band Hubbard model, in comparison with CT-QMC and exact diagonalization. We also analyze the impact of the bath discretization and conclude that the new method appears most promising for cluster DMFT studies at low temperatures.
[1] E. Khatami et al., PRE 81, 056703 (2010); QUantum Electron Simulation Toolbox, http://www.cs.ucdavis.edu/∼bai/QUEST_public/.
R. Blankenbecler, D. J. Scalapino, and R. L. Sugar, Phys. Rev. D 24, 2278 (1981).