Optimal Electron Density Mechanism for Hydrogen on the Surface and at a Vacancy in Tungsten

In terms of first-principles investigation of H-tungsten (W) interaction, we reveal a generic optimal electron density mechanism for H on W(110) surface and at a vacancy in W. Both the surface and vacancy internal surface can provide a quantitative optimal electron density of ∼0.10 electron/ų for H binding to make H stability. We believe that such a mechanism is also applicable to other surfaces such as W(100) surface because of the (100) surface also providing an optimal electron density for H binding, and further likely actions on other metals.