Room-Temperature Structures of Solid Hydrogen at High Pressures

Abstract

By employing first-principles metadynamics simulations, we explore the 300 K structures of solid hydrogen over the pressure range 150-300 GPa. At 200 GPa, we find the ambient-pressure disordered hexagonal close-packed (hcp) phase transited into an insulating partially ordered hcp phase (po-hcp), a mixture of ordered graphene-like H2 layers and the other layers of weakly coupled, disordered H2 molecules. Within this phase, hydrogen remains in paired states with creation of shorter intra-molecular bonds, which are responsible for the very high experimental Raman peak above 4000 cm-1. At 275 GPa, our simulations predicted a transformation from po-hcp into the ordered molecular metallic Cmca phase (4 molecules/cell) that was previously proposed to be stable only above 400 GPa. Gibbs free energy calculations at 300 K confirmed the energetic stabilities of the po-hcp and metallic Cmca phases over all known structures at 220-242 GPa and >242 GPa, respectively. Our simulations highlighted the major role played by temperature in tuning the phase stabilities and provided theoretical support for claimed metallization of solid hydrogen below 300 GPa at 300 K.

Accepted in Journal of Chemical Physics

References in corpus (10)

• Predicting crystal structures: the Parrinello-Rahman method revisited
• A superconductor to superfluid phase transition in liquid metallic hydrogen
• A quantum fluid of metallic hydrogen suggested by first-principles calculations
• Zero-Temperature Structures of Atomic Metallic Hydrogen
• Density functional theory study of phase IV of solid hydrogen
• Stable liquid Hydrogen at high pressure by a novel ab-initio molecular dynamics
• Quantum and Classical Orientational Ordering in Solid Hydrogen
• Quasi-molecular and atomic phases of dense solid hydrogen
• Metric-tensor flexible-cell algorithm for isothermal-isobaric molecular dynamics simulations
• Dipole-quadrupole interactions and the nature of phase III of compressed hydrogen

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