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Renormalization group studies and Monte Carlo simulation for quantum spin systems

Thesis/Dissertation ·
OSTI ID:7247264
Extended application of various real-space renormalization group methods to quantum spin systems is discussed. At finite temperature, both the reliability and range of application of the decimation renormalization group method (DRG) are extended for calculating the thermal and magnetic properties of low-dimensional quantum spin chains, in which general models of the three-state Potts model and the general Heisenberg model are proposed. Some interesting finite-temperature behavior of the models was obtained. Also proposed is a general formula for the critical properties of the n-dimensional q-state Potts model by using a modified Migdal-Kadanoff approach which is in very good agreement with all available results for general q and d. For high-spin systems, the famous Haldane's prediction was studied by using a modified block renormalization group approach in spin-1/2, spin-1, and spin-3/2 cases. The results supports Haldane's prediction and a novel property of the spin-1 Heisenberg antiferromagnet has been predicted. A modified quantum Monte Carlo simulation approach was developed in this study and used to treat quantum interacting problems (only quantum spin systems are studied) without the negative sign problem.
Research Organization:
Utah State Univ., Logan (USA)
OSTI ID:
7247264
Country of Publication:
United States
Language:
English