Difficulties of the Independent-Particle Model in the Description of Energetic Transitions in Atoms

It is shown that the first-order correlation correction to the transition matrix element between two nonpenetrating states can be written in a completely parametrized form. The correction is directly proportional to the square of the transition energy and to the dipole polarizability of the core. It follows that for sufficiently energetic transitions the magnitude of the correction becomes as large as the zero-order matrix element.