Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 27: CE: Poster Session
TT 27.41: Poster
Mittwoch, 24. März 2010, 14:00–18:00, Poster D1
Calculating Thermodynamic Properties using Stochastic Sampling within the DMRG framework — •Stefan Kremer1,2 and Peter Schmitteckert3 — 1Institut für Theorie der Kondensierten Materie, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany — 2Laboratoire CRISMAT, UMR 6508 CNRS-ENSICAEN, and IRMA, Caen, France — 3Institut für Nanotechnologie, Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany
In order to calculate thermodynamic properties a method within the framework of the Density Matrix Renormalisation Group (DMRG) is proposed. This method combines the Imaginary Time Evolution with the ideas of Stochastic State Sampling proposed by J. Jaklič and P. Prelovšek. In their approach obtaining thermodynamic states within Exact Diagonalisation is accomplished by the means of stochastic sampling of the Hilbert space. Thermodynamic expectation values of conserved quantities at a specific temperature can then be evaluated since they correspond to the quantum mechanical expectation values with respect to such states. Performing an evolution of the states in imaginary time will therefore represent a cooling of the system. In the proposed method the Hilbert space is sampled stochastically where the low energy region is sampled with a higher weight for the purpose of evaluating the thermodynamic expectation values at low temperature. Results for the specific heat of spinless fermionic rings are compared to predictions from Exact Diagonalisation.