Sa. Ktitorov et L. Jastrabik, TODA LATTICE INVARIANTS AND THE HARPER HAMILTONIAN THERMODYNAMICS, Journal of physics. A, mathematical and general, 27(16), 1994, pp. 5687-5692
A connection between the Toda lattice additive integrals of motion and
the Harper's Hamiltonian thermodynamics is established. The Harper's
Hamiltonian is shown to be a special case of the Lax operator for the
Toda lattice.