2002/07/22 by Frank Brechtefeld, Brechtefeld, Frank
Chemistry · Materials Science · #Advanced NMR Techniques and Applications #FOS: Physical sciences #High Energy Physics - Lattice (hep-lat) #Magnetism in coordination complexes #Molecular spectroscopy and chirality
paper · pdf · doi:10.48550/arxiv.hep-lat/0207012
openalex publication_date 2002/07/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The two-dimensional O(3) model at a vacuum angle theta=pi is investigated. This model has a severe sign problem. By a Wolff cluster algorithm an integer or half-integer topological charge is assigned to each cluster. The meron clusters (clusters with half-integer topological charge) are used to construct an improved estimator for the correlation function of two spins at theta=pi. Only configurations with 0 and 2 merons contribute to this correlation function. An algorithm, that generates configurations with only 0 and 2 merons, is constructed and numerical simulations at theta=pi are performed. The numerical results indicate the presence of long range correlations at theta=pi.