First-Principles Calculations on the Wettability of Li Atoms on the (111) Surfaces of W and Mo Substrates

Comprehension over the interactions between lithium (Li) atoms and tungsten (W) or molybdenum (Mo) are crucial to improve the wettability of the flowing liquid Li, a candidate plasma facing material in fusion devices, on the surfaces of supported substrate metals. In this work, we utilize first-principles density- functional theory calculations to figure out the adsorption and diffusion properties of Li atoms and clusters on the (111) surfaces of W and Mo. It is found that single Li atom in the fcc-hollow site is the most favored configuration. For the multiple Li atoms adsorption on the substrates, the planar construction is more stable than the stacking one. The electronic structure analysis shows that the lateral interaction between Li atoms is very weak and the binding between Li atom and the substrates is strong; therefore, it can be inferred that the liquid Li is “wetting” intrinsically on the surfaces of the W and Mo substrates. We also investigate the effect of defects (vacancy, H, C, and O) and find that the preexisted vacancy in the substrates has little effect on the wettability; however, the impurities (especially O atom) will hinder the movement of Li atoms on the metal substrates.