Quantum Effects and Critical Behavior in Low-Dimensional Spin-1/2 Systems
G. Kamieniarz, G. Musial, L. Dębski, M. Bieliński
Computational Physics Division, Institute of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland

and R. Dekeyser
Instituut voor Theoretische Fysica, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
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The critical coupling and spontaneous magnetization curve for the 2D-Ising model are calculated using the effective-field method with correlations. An application of the method to the quantum S=1/2 1D-Heisenberg model is presented and reliable low-temperature estimates of the specific heat are evaluated.
DOI: 10.12693/APhysPolA.92.445
PACS numbers: 64.60.-i, 75.10.Hk, 75.10.Jm, 75.40.Mg