Evaluation of first-principles techniques for obtaining materials parameters of α -uranium and the (001) α -uranium surface

First-principles calculations based on the projector augmented-wave (PAW) technique have been applied to the prediction of materials properties of $\ensuremath{\alpha}$-uranium and its (001) surface. The results of the PAW calculations are shown to be comparable in accuracy to the full-potential calculations reported elsewhere. In addition to calculating lattice constants and elastic moduli, the vacancy formation energy $(1.95\phantom{\rule{0.3em}{0ex}}\mathrm{eV})$, (001) surface relaxation ($\ensuremath{-}3.5%$ for ${\ensuremath{\delta}}_{12}$ and $+1.2%$ for ${\ensuremath{\delta}}_{23}$), (001) surface energy $(1.4\phantom{\rule{0.3em}{0ex}}\mathrm{J}∕{\mathrm{m}}^{2})$, and (001) work function $(3.6\phantom{\rule{0.3em}{0ex}}\mathrm{eV})$ were also obtained. The overall agreement with experiment is satisfactory. Using an elastic model for brittle-crack failure, a yield stress of $430\phantom{\rule{0.3em}{0ex}}\mathrm{MPa}$ was estimated. Further exploration of materials failure modes (such as plastic deformation) awaits a larger-scale atomistic treatment. Full spin-orbit and scalar relativistic calculations were shown to give results with similar levels of accuracy compared to experiment.