Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 78: Correlated Electrons: Poster Session

TT 78.33: Poster

Donnerstag, 10. März 2016, 15:00–18:30, Poster D

Cluster Perturbation Theory for Spin Systems — •Benjamin Lenz, Salvatore R. Manmana, and Thomas Pruschke — Institute for Theoretical Physics, Georg-August-Universität Göttingen, Germany

Quantum cluster methods such as Cluster Perturbation Theory (CPT) or Variational Cluster Approximation (VCA) have been broadly applied to electron systems, but there are just very few applications to spin systems so far. Using Larkin’s equations, a first order perturbation theory in cluster-cluster interactions can be constructed for spin systems and in a first attempt, dimerized Heisenberg chains have been addressed within CPT [1]. Here, we first benchmark the spectral functions and magnetization curves obtained for the Heisenberg XXZ chain by checking with exact Bethe ansatz results. Furthermore, we present CPT studies on Heisenberg zig-zag-ladders, which possess intriguing properties at high magnetic fields, and compare our findings with exact diagonalization.

Financial support via DFG through FOR1807 is gratefully acknowledged.
A. S. Ovchinnikov, I. G. Bostrem, V. E. Sinitsyn,

Theor. Math. Phys. 162, 179 (2010).