Core Scattering in Elliptic States:
The quantum state being investigated has principal quantum number n=15, and has angular momentum and magnetic quantum numbers l = m = 14.
The hydrogen state on the left is being pulled and stretched upward, and then downward, in a regular fashion. This regular deformity of the state is called "Stark oscillation." The hydrogen atom, consisting only of an electron and a proton in the nucleus, shows a relatively simple oscillation motion that can be understood using basic quantum mechanics.
The sodium state on the right is also undergoing Stark oscillations,
but we also see scattering effects: Notice that when the state is
fully stretched out, we see that part of the state quickly
"precesses" and appears on the other side of the nucleus.
This precession occurs because in addition to interacting with
the nucleus, the outer electron in the sodium atom will also feel
the influence of the inner electrons, referred to as the atomic "core."
It is the presence of this core that makes the motion of the sodium state
more complicated than the motion in hydrogen.
More information on the motions of circular states in an
applied electric field can be found in the paper:
Visualization of the core-scattering dynamics of Rydberg wave packets
J. A. West and C. R. Stroud , Jr.
Optics Express 1, 31 (1997).
Wave packet fractional revivals
Classical vs. Hydrogenic