Quantization conditions for the periodic Toda chain: Inadequacy of Bethe ansatz methods

Abstract

Gutzwiller has developed a scheme for determining the energy levels of a finite quantum Toda lattice. We present a numerical analysis using his method and calculate low-lying energy levels for some small lattices. We check the completeness of his quantization conditions in the harmonic (low-energy) and the semiclassical (high-energy) limits. Our main finding is that the Bethe-ansatz spectrum equations, known to be exact for an infinite Toda lattice in the classical limit, are incorrect for finite and quantum lattices.