Electronic, mechanical, and thermodynamic properties of americium dioxide

By performing density functional theory (DFT) +U calculations, we systematically study the electronic, mechanical, tensile, and thermodynamic properties of AmO₂. It is found that the chemical bonding character in AmO₂ is similar to that in PuO₂, with smaller charge transfer and stronger covalent interactions between americium and oxygen atoms. The stress-strain relationship of AmO₂ is examined along the three low-index directions, showing that the [1 0 0] and [1 1 1] directions are the strongest and weakest tensile directions, respectively, but the theoretical tensile strengths of AmO₂ are smaller than those of PuO₂. The phonon dispersion curves of AmO₂ are calculated and the heat capacities as well as lattice expansion curve are subsequently determined. The lattice thermal conductivity of AmO₂ is further evaluated and compared with attainable experiments. Our present work integrally reveals various physical properties of AmO₂ and can be referenced for technological applications of AmO₂ based materials.