The classical Coulomb three-body problem in the collinear eZe configuration

We investigate the classical dynamics of a two-electron atom and ions H-, He, Li+, Be2+, . . . , in the collinear eZe configuration. We consider the case that the masses of all particles are finite. It is revealed that the mass ratio xi between the nucleus and electron plays an important role for the dynamical behaviour of these systems. With the aid of an analytical tool and numerical computation, it is shown that, thanks to a large mass ratio xi, the classical dynamics of these systems is fully chaotic, probably hyperbolic. Experimental evidence of this finding is also proposed.