Chaos in a supercritical atom

Stochastization of a supercritical atom (with a nuclear charge number Z in excess of 137) under the effect of a periodic perturbation is investigated. The Hamiltonian for a relativistic electron in the Coulomb field of a Z>137 charge is obtained. A simple analytic formula is derived for the critical external-field strength corresponding to the onset of stochastization. The diffusion coefficient is evaluated.