S. J. Mitchell, M. A. Novotny, José D. Muñoz Center for Materials Research and Technology and Department of Physics, Florida State University, Tallahassee, Florida 32306-4351, USA Supercomputer Computations Research Institute, Florida State University, Tallahassee, Florida 32306-4130, USA Institute for Computer Applications 1, University of Stuttgart, D-70569 Stuttgart, Germany Permanent addres...

We present a construction of integrable quantum spin chains where local spin-spin interactions are weighted by “position”-dependent potential containing abelian non-local spin dependance. This construction applies to the previously defined three general quadratic reflection-type algebras: respectively non-dynamical, semidynamical, fully dynamical. e-mail: [email protected] e-mail: [email protected]...

The one-dimensional spin-1 Heisenberg antiferromagnetic chain is studied by a Green's function technique. The excitation spectrum is obtained. The dispersion of excitations for an infinite isotropic chain is numerically calculated. At k ˆ 0 we obtain a gap 2D which is equal to 0:826J and at k ˆ p we obtain D ˆ 0:41J, which is in very good agreement with the exact numerical results of White and ...

In this paper we develop some random walk representations for the spin-S Heisenberg ferromagnet with nearest neighbor interaction on the integer lattice in d dimensions. The representations parallel corresponding representations for the perfect Bose gas. Hence the Heisenberg model can be thought of as an interacting Bose gas. This has been made more explicit in the paper of Dyson (5/ (see also ...