Screening of an oscillating external electric field in atoms

We study the screening of a homogeneous oscillating external electric field E0 in noble-gas atoms using atomic many-body calculations. At zero frequency of the oscillations (ω=0) the screened field E(r) vanishes at the nucleus, E(0)=0. However, the profile of the field E(r) is complicated, with the magnitude of the field exceeding the external field E0 at certain points. For ω>0 the field E(r,ω) strongly depends on ω and at some points may exceed the external field E0 many times. The field at the nucleus is not totally screened and grows with ω faster than ω2. It can even be enhanced when ω comes close to resonance with a frequency of an atomic transition. This field interacts with CP-violating nuclear electric dipole moments creating new opportunities for studying them. The screening of the external field by atomic electrons may strongly suppress (or enhance near an atomic resonance) the low energy nuclear electric dipole transitions.