Spin-pair Correlations for the Low-Dimensional Quantum XXZ Model : General and Mathematical Physics

概要

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Nearest neighbour spin-pair correlations for the S-1/2 Ising-like and XY-like system of a linear chain and for the XY-like system of a square lattice are obtained as a function of temperature by the second-order Green's function method. The transverse correlation and the specific heat for the XY model of a linear chain are in good agreement with rigorous results except for quite low temperatures. The longitudinal correlation for the XY model of a square lattice is given by -0.07311 in the ground state in fair agreement with -0.076±0.002 by the finite lattice method and with -0.0714 by the variational method. For the XY-like system of a square lattice the longitudinal nearest neighbour correlation in the ground state becomes always negative. The possibility of a transition of a certain kind is predicted near the Heisenberg limit for a square lattice but not for a linear chain.
理論物理学刊行会の論文
1989-05-25