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Dynamic spin correlation functions of the XYZ chain at infinite temperature: A study based on moments

1986; Elsevier BV; Volume: 136; Issue: 2-3 Linguagem: Inglês

10.1016/0378-4371(86)90254-2

1873-2119

JoséM.R. Roldan, Barry M. McCoy, Jacques H. H. Perk,

Quantum many-body systems

For infinite temperature we calculate the terms up to order t10 in the expansion of the correlation function 〈σz0(t)σzn(0)〉 of the anisotropic spin - 12 Heisenberg chain. These expansion coefficients are analyzed using the theory of Tchebycheff bounds. For the isotropic Heisenberg chain, where longer series are available, the Tchebycheff bounds are also calculated. These bounds are then used to assess the various phenomenological approximation schemes commonly used to discuss spin diffusion.