5f electron localization-delocalization transition from UPd3 to UPt3

The electronic structures of URh3, UPd3, UPt3 and UAu3 are calculated with the self-interaction-corrected local-spin-density approximation. We find that only in URh3 the f-electrons are fully delocalized. UPt3 has one f-electron localized at each U site, whilst a localized f2 configuration of the U-ion is found for UPd3. It is predicted that upon application of pressure, UPd3 will acquire the f1 configuration and possibly exhibit heavy-fermion behaviour. We find that UAu3 is characterized by the same mixed localized-delocalized f-electron manifold as UPd3. (author)