The Henon-Heiles Hamiltonian was introduced in 1964 [M. Henon, C. Heiles, A
stron. J. 69 (1964) 73] as a mathematical model to describe the chaotic mot
ion of stars in a galaxy. By canonically transforming the classical Hamilto
nian to a Birkhoff-Gustavson normal form, Delos and Swimm obtained a discre
te quantum mechanical energy spectrum. The aim of the present work is to fi
rst quantize the classical Hamiltonian and to then diagonalize it using dif
ferent variants of flow equations, a method of continuous unitary transform
ations introduced by Wegner in 1994 [Ann. Physik (Leipzig) 3 (1994) 77]. Th
e results of the diagonalization via flow equations are comparable to those
obtained by the classical transformation. In the case of commensurate freq
uencies the transformation turns out to be less lengthy. In addition, the d
ynamics of the quantum mechanical system are analyzed on the basis of the t
ransformed observables. (C) 1999 Elsevier Science B.V. All rights reserved.