First-principles study on Ga interactions with Pu surfaces and δ-Pu bulk

The Ga-Pu alloy presents a potential solution to address the constraints of Pu metal as a fuel. Therefore, it is imperative to investigate its pertinent properties. In research, surface models were commonly employed for the preliminary exploration of information, including the identification of more stable binding sites. First-principles calculation methods were employed to investigate the adsorption characteristics of Ga atoms at various sites on the surfaces of Pu(100), Pu(110), and Pu(111), as well as their binding behavior within the Plutonium unit cells. The analysis, by adsorption energies, Charge Density Difference, Bader Charge, Electron Localization Function (ELF), Reduced Density Gradient (RDG), and Projected Density of States (PDOS), revealed that when Ga atoms interacted with the surface, they tended to bind more strongly to the Pu(100) long-bridge and Pu(110) TOP 1 sites, with adsorption energies of -2.585eV and -3.150eV, respectively. On the Pu(111) surface, the adsorption energies at the three sites were adsorption comparable, and the binding trends were similar. Upon entering the δ-Pu unit cells, Ga atoms formed a more stable structure after combining at the G, H, and I sites. The stability both on the surfaces and within the δ-Pu unit cells was primarily attributed to metallic bonds, with an additional contribution from mutual attraction due to van der Waals forces in surface adsorption. The adsorption behavior of Ga on the Pu surface and its binding within the δ-Pu unit cell was systematically investigated. This exploration aimed to offer ideas and insights for a comprehensive understanding of Ga-Pu alloys in subsequent studies.