Adsorption, diffusion, and limited dissociation of a single water molecule on the α-Pu₂O₃ (1 1 1) surface

We have investigated the adsorption, diffusion and dissociation of single water molecule on the α-Pu₂O₃ (1 1 1) surface using DFT  +  U approach. We show that, with very low absorption energies, the H₂O molecule prefers to be absorbed at the surface oxygen vacancies. We futher reveal that the electrons transferred from the H₂O molecule to the surface Pu atom mostly belong to the O atom in H₂O. We also find that diffusion energy barriers are very low, indicating that the adsorbed H₂O molecules are easy to diffuse. The trajectories obtained from ab initio molecular dynamics (AIMD) and the dissociation barrier calculated using nudged elastic band (NEB) methods both show that the absorbed H₂O prefers to dissociate into hydrogen atom and hydroxyl group, other than into hydrogen molecule and oxygen atom. The present work suggests that the absorbed H₂O easily diffuses but dissociates limitedly on the the α-Pu₂O₃ (1 1 1) surface.