Rare-Earth and Transuranic Elements

The possible existence of a second rare-earth-like group of elements beginning with uranium and extending to the transuranic elements, is discussed by a calculation of the atomic eigen-functions of the 4f and 5f electrons. Energy and spatial extension of the 4f eigenfunctions drop suddenly at the beginning of the rare-earth group; the binding energy is calculated to be 0. 95 ev in lanthanum, Z=57, and 5 ev in neodymium, Z=60. The 5f eigenfunctions undergo the same type of change around Z=92. The binding energies were calculated to be 1. 35 ev for Z=86, 8. 5 ev for Z=91 and 14 ev for Z=93.