Structural, magnetic, electronic, and elastic properties of face-centered cubic PuHx (x = 2, 3): GGA (LSDA) + U + SO

We perform first-principles calculations to investigate the structural, magnetic, electronic, and mechanical properties of face-centered cubic (fcc) PuH2 and fcc PuH3 using the full potential linearized augmented plane wave method (FP-LAPW) with the generalized gradient approximation (GGA) and the local spin density approximation (LSDA) taking account of both relativistic and strong correlation effects. The optimized lattice constant a0 = 5.371 Å for fcc PuH2 and a0 = 5.343 Å for fcc PuH3 calculated in the GGA + sp (spin polarization) + U (Hubbard parameter) + SO (spin—orbit coupling) scheme are in good agreement with the experimental data. The ground state of fcc PuH3 is found to be slightly ferromagnetic. Our results indicate that fcc PuH2 is a metal while fcc PuH3 is a semiconductor with a band gap about 0.35 eV. We note that the SO and the strong correlation between localized Pu 5f electrons are responsible for the band gap of fcc PuH3. The bonds for PuH2 have mainly covalent character while there are covalent bonds in addition to apparent ionicity bonds for PuH3. We also predict the elastic constants of fcc PuH2 and fcc PuH3, which were not observed in the previous experiments. (condensed matter: electronic structure, electrical, magnetic, and optical properties)