Comment on ‘‘Regular and chaotic motions in ion traps: A nonlinear analysis of trap equations’’

Using Lie-group and prolongation techniques, Baumann and Nonnenmacher [Phys. Rev. A 46, 2682 (1992)] recently studied integrability of a Hamiltonian describing the dynamics of ion traps. It is pointed out that their results can be obtained more simply and directly by recognizing that the problem is separable in each of the integrable limits found by Baumann and Nonnenmacher. Similarities between this system and a hydrogen atom in a generalized van der Waals potential are also considered.