Regensburg 2000 – scientific programme

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TT: Tiefe Temperaturen

TT 17: Postersitzung II: Pinning und Vortexdynamik (1-8), Supraleitung: Theorie (9-13), Korrelierte Elektronen (14-48), Niederdimensionale Systeme (49-68), Quantenflüssigkeiten (69-75)

TT 17.66: Poster

Wednesday, March 29, 2000, 14:30–18:00, A

On the evaluaton of the specific heat and general off-diagonal n-point correlation functions within the loop algorithm — •Vicente Alvarez and Claudius Gros — Fachbereich Physik, Universität des Saarlandes, 66041 Saarbrücken

We present an efficient way to compute diagonal and off-diagonal n-point correlations functions for quantum spin-systems within the loop algorithm. We show that the general rules for the evaluation of these correlation functions take an especially simple form within the framework of directed loops. These rules state that contributing loops have to close coherently. As an application we evaluate the specific heat for the case of the spin-ladder compound Sr₁₄Cu₂₄O₄₁. We show, that the evaluation of improved estimators for the off-diagonal four-point correlation functions contributing to the specific heat results in a gain of roughly one order of magnitude in computational effort with respect to more standard methods of evaluating the specific heat within quantum Monte Carlo simulations.