Ab initio random structure searching using density functional theory is used to determine the ground-state structures of atomic metallic hydrogen from 500 GPa to 5 TPa. Including proton zero-point motion within the harmonic approximation, we estimate that molecular hydrogen dissociates into a monatomic body-centered tetragonal structure near 500 GPa ($r_s=1.23$) that remains stable to 1 TPa ($r_s=1.11$). At higher pressures, hydrogen stabilizes in an $\dots ABCABC\dots$ planar structure that is similar to the ground state of lithium, but with a different stacking sequence. With increasing pressure, this structure compresses to the face-centered cubic lattice near 3.5 TPa ($r_s=0.92$).

• Received 22 November 2010

DOI:https://doi.org/10.1103/PhysRevLett.106.165302