Date of Original Version
The frequency‐dependent spin autocorrelation functions for the 1D s=1/2 Heisenberg and XY models at zero temperature are determined by the recursion method. These applications further demonstrate the efficacy of a new calculational scheme developed for the termination of continued fractions. A special feature of the recursion method highlighted here is its capability to predict the exponent of the infrared singularities in spectral densities.
V. S. Viswanath and Gerhard Müller. The recursion method applied to the T=0 dynamics of the 1D s=1/2 Heisenberg and XY models. J. Appl. Phys. 70 (1991), 6178-6180.
Available at: http://dx.doi.org/10.1063/1.350036