Structural properties, superconductivity, and magnetism of metallic hydrogen

The electronic band structure and structural properties of paramagnetic metallic hydrogen in the simple cubic (sc), fcc, bcc, and hcp phases have been determined theoretically using our bulk fullpotential total-energy linearized augmented-plane-wave method. In the density range corresponding to $1<\mathrm{}{r}_s<2\mathrm{}$ we find a phase transition from sc to hcp at high pressure which indicates the importance of the hcp structure in phase transformations of molecular hydrogen under pressure. Superconducting transition temperatures up to 250 K are predicted within the framework of the rigid-ion approximation. An analysis of the Stoner factor shows the expected magnetic instability in the low-density region.