Adsorption and dissociation behavior of H₂ on PuH₂ (100), (110) and (111) surfaces: a density functional theory+U...

The density functional theory (DFT) and DFT plus correction for on-site Coulomb interaction (DFT+U) method were performed to investigate the adsorption and dissociation of H₂ on PuH₂ (100), (110) and (111) surfaces. Overall, the H₂ molecule can be adsorbed on the PuH₂ surface without spontaneous dissociation. The calculated H-H bond lengths (R _H-H) are all elongated to different degrees, and the R _H-H at different adsorption sites is about 0.84-4.21% longer than in the gas phase. We found that the dissociation of H₂ on the (110) surface is a spontaneous exothermic process, and a total energy of 0.60 eV is released in the whole process. The smaller barriers corroborate that the migration of an H atom on the PuH₂ surface is possible, and even spontaneous diffusion may occur. The spontaneous migration of a hydrogen atom adsorbed on the (110) surface from the surface to the interior promotes the conversion of PuH₂ to PuH₃, which may be the fundamental driving force of hydrogenation corrosion. Our results provide useful information to explain the mechanism of hydrogenation corrosion on the PuH₂ surface.