Adsorption and dissociation behavior of H(2) on PuH(2) (100), (110) and (111) surfaces: a density functional theory+U study

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 H(2) on PuH(2) (100), (110) and (111) surfaces. Overall, the H(2) molecule can be adsorbed on the PuH(2) 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 H(2) 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 PuH(2) 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 PuH(2) to PuH(3), which may be the fundamental driving force of hydrogenation corrosion. Our results provide useful information to explain the mechanism of hydrogenation corrosion on the PuH(2) surface.