On the Sign Problem in the Hirsch-Fye Algorithm for Impurity Problems

Jaebeom Yoo 1, Shailesh Chandrasekharan 1, Ribhu K. Kaul 1, Denis Ullmo 1, 2, Harold U. Baranger 1

Journal of Physics A 38 (2005) 10307-10310

We show that there is no fermion sign problem in the Hirsch and Fye algorithm for the single-impurity Anderson model. Beyond the particle-hole symmetric case for which a simple proof exists, this has been known only empirically. Here we prove the nonexistence of a sign problem for the general case by showing that each spin trace for a given Ising configuration is separately positive. We further use this insight to analyze under what conditions orbitally degenerate Anderson models or the two-impurity Anderson model develop a sign.

  • 1. Duke Physics,
    Duke University
  • 2. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS),
    CNRS : UMR8626 – Université Paris XI – Paris Sud
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