  The equation of state, structural behavior and phase stability of
{\alpha}-uranium have been investigated up to 1.3 TPa using density functional
theory, adopting a simple description of electronic structure that neglects the
spin-orbit coupling and strong electronic correlations. The comparison of the
enthalpies of Cmcm (alpha-U), bcc, hcp, fcc, and bct predicts that the aplpha-U
phase is stable up to a pressure of ~285 GPa, above which it transforms to a
bct-U phase. The enthalpy differences between the bct and bcc phase decrease
with pressure, but bcc is energetically unfavorable at least up to 1.3 TPa, the
upper pressure limit of this study. The enthalpies of the close-packed hcp and
fcc phases are 0.7 eV and 1.0 eV higher than that of the stable bct-U phase at
a pressure of 1.3 TPa, supporting the wide stability field of the bcc phase.
The equation of state, the lattice parameters and the anisotropic compression
parameters are in good agreement with experiment up 100 GPa and previous
theory. The elastic constants at the equilibrium volume of alpha-U confirm our
bulk modulus. This suggests that our simplified description of electronic
structure of uranium captures the relevant physics and may be used to describe
bonding and other light actinides that show itinerant electronic behavior
especially at high pressure.
