Electron-electron interaction and localization in d and f transition metals

We discuss, for the d and f transition metals, the competition between atomiclike electrostatic Coulomb and exchange interactions and loss of atomic characteristics in the solid through screening of f and d charge fluctuations and hybridization. We derive semiempirical relations describing these interactions for the 3d, 4d, 5d, 4f, and 5f elements in the environment of a metallic host. We then compare these to the hybridization widths, also semiempirically determined, and arrive at conclusions concerning the localization of the d or f electrons and the formation of magnetic moments. We show that some of the light actinides can exhibit negative $U^{\mathrm{eff}}$ behavior dependent on their valence in the solid. We argue that some d transition metals may belong to the same group if properly alloyed.