Journal of Physics A Mathematical and Theoretical
A τ-function on the inhomogeneous lattice and the classical isotropic Heisenberg spin chain
Atsushi Mukaihira
Abstract
A τ-function on the inhomogeneous lattice is introduced by a deformation of that of the Toda lattice hierarchy. An associated discrete-time integrable system is constructed in Sato and Lax formalisms. It is shown that a one-dimensional reduction of the system gives a Bäcklund transformation of the classical isotropic Heisenberg spin chain, which is equivalent to the R II -chain proposed by Spiridonov and Zhedanov.