REGULARITY AND CHAOS IN THE CENTER OF MASS MOTION OF THE HYDROGEN-ATOM IN A MAGNETIC-FIELD

What does the center of mass motion of the hydrogen atom in a magnetic field look like? Is it similar to the uniform straight-lined motion of the field-free case or does is perform only tiny vibrations? We show that there is a great variety in the center of mass motion. For regular electronic motion only a bounded range of phase space is available for the center of mass coordinate. There exist many different types of regular center of mass behavior according to the values of the magnetic field strength, energy and angular momentum. At the onset of chaos in the electronic motion a prominent transition to chaos in the center of mass motion is observed. In the fully chaotic regime the trajectories of the center of mass exhibit many properties of a random motion and fill up the unbounded coordinate space. In particular, we obtain a linear diffusion law for the spreading of an ensemble of center of mass trajectories.