Pressure-induced electronic and structural phase transitions in solid hydrogen

Possible induced electronic and structural phase transitions in solid hydrogen are studied using a unified theoretical approachthe local-density total-energy full-potential linearized-augmented-plane-wave methodwhich has the precision to treat the highly anisotropic Pa3 molecular phase on the same footing as the monatomic close-packed phases. The pressure-induced metallization by band overlap and bond length relaxation within the Pa3 structure of molecular solid hydrogen is described and discussed; the calculations predict an insulator-to-metal phase transition at 1.70.2 Mbar. At a much higher pressure of 41 Mbar, a structural phase transition takes place to a monatomic metallic hcp phase with a high superconducting transition temperature.