First-Principles Study on the Adsorption and Dissociation Behavior of H2 on the Surface of a Plutonium–Gallium System

In order to understand the mechanism of hydrogen interaction on the surface of a plutonium–gallium system, the adsorption and dissociation behaviors of hydrogen molecules on the surface of a plutonium–gallium system were studied using the first-principles approach. The results show that the physical adsorption of hydrogen molecules occurs on the surface with a small degree of interaction; the most stable adsorption configuration is hollow-site parallel adsorption (H-b-hor1). During adsorption, charge transfer occurs mainly in the first atomic layer, and the density of states and surface function does not change significantly before and after adsorption. When the hydrogen molecule overcomes the energy barrier of 4.96 eV, it dissociates into two hydrogen atoms chemisorbed on the surface, which reduces the energy of the whole system by 1.95 eV. The essence of the hydrogen atom–surface interaction is that the 1s orbital of the hydrogen atom hybridizes with the 4s and 4p orbitals of the gallium atom and the 6s, 7s, and 6d orbitals of the plutonium atom to form a chemical bond.