  Systematically studying the crystal, magnetic, and electronic structures of
PuGa3 with density functional theory (DFT) reveals the entanglement of the
three types of structure. Magnetic structure affects the energy more strongly
than crystal structure. For DFT to correctly order the crystal structures in
agreement with experiment requires special treatment of the electronic
correlation in the 5f states, exemplified here by the GGA+U approach. The upper
and lower Hubbard bands change with increasing U in very dissimilar ways for
the two most different crystal structures. The results suggest the
effectiveness of using magnetic structure to simulate correlation effects in
the actinides depends on both the magnetic and the crystal structure.
