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

Abstract

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.