Stability and optical properties of plutonium monoxide from first-principle calculation.

The resolution of questions about the existence of condensed plutonium monoxide (PuO) has long been hindered by lack of thermochemical data. Here we perform first-principles calculation to investigate the reaction PuO + Pu → 3 PuO and find that PuO is thermodynamically unstable under ambient pressure. We also find that pressure could stabilize PuO by strengthening the hybridization between Pu-5f/6d and O-2p states. Moreover, the dynamical stability of NaCl-type PuO is verified by the phonon calculation. Optical properties such as reflectivity are also predicted for the detection of metallic PuO.