QUASI-EXACTLY-SOLVABLE QUANTUM LATTICE SOLITONS

We extend the exactly solvable Hamiltonian describing f quantum oscillators considered recently by J. Dorignac et al. We introduce a new interaction which we choose to be quasi-exactly solvable. The properties of the spectrum of this new Hamiltonian are studied as functions of the new coupling constant. We point out that both the original and the by us modified Hamiltonians are related to adequate Lie structures.