Features of the Spectral Density of a Spin System

Abstract

The relationship between the spectral density and the free energy of a spin system is analyzed. Analytical expressions for calculating the spectral density for exactly solvable models are derived. The approach is tested as applied to the one-dimensional Ising model. Additionally, the approach is used to analyze the spectral density of the two-dimensional Ising model, the Bethe-lattice model, and the mean-field model. It is shown that even a small change in the spectral density is able to radically change the parameters of the system.