Bonding, structures, and band gap closure of hydrogen at high pressures

Abstract

We have studied dense hydrogen and deuterium experimentally up to 320 GPa and using ab initio molecular dynamic (MD) simulations up to 370 GPa between 250 and 300 K. Raman and optical absorption spectra show significant anharmonic and quantum effects in mixed atomic and molecular dense phase IV of hydrogen. In agreement with these observations, ab initio MD simulations near 300 K show extremely large atomic motions, which include molecular rotations, hopping and even pair fluctuations suggesting that phase IV may not have a well-defined crystalline structure. The structurally diverse layers (molecular and graphene-like) are strongly coupled thus opening an indirect band gap; moreover, at 300 GPa we find fast synchronized intralayer structural fluctuations. At 370 GPa the mixed structure collapses to form a metallic molecular Cmca-4 phase, which exhibit a new interstitial valence charge bonding scheme.

Main manuscript: 20 pages, 13 figures

References in corpus (4)

• A superconductor to superfluid phase transition in liquid metallic hydrogen
• Density functional theory study of phase IV of solid hydrogen
• Maximally-localized Wannier functions for GW quasiparticles
• Room-Temperature Structures of Solid Hydrogen at High Pressures

Cited by in corpus (19)

• High-Temperature Superconductivity in Alkaline and Rare Earth Polyhydrides at High Pressure: A Theoretical Perspective
• Variational and Diffusion Quantum Monte Carlo Calculations with the CASINO Code
• Towards a Predictive First-Principles Description of Solid Molecular Hydrogen with Density-Functional Theory
• Proton Transfer in Phase IV of Solid Hydrogen and Deuterium
• Nature of the Metallization Transition in Solid Hydrogen
• Quantum Monte Carlo Study of High Pressure Solid Molecular Hydrogen
• Coupled Electron-Ion Monte Carlo simulation of hydrogen molecular crystals
• Energy gap closure of crystalline molecular hydrogen with pressure
• The role of van der Waals and exchange interactions in high-pressure solid hydrogen
• Appraisal of the realistic accuracy of Molecular dynamics of high pressure hydrogen
• Theory of high pressure hydrogen, made simple
• Unconventional phase III of high-pressure solid hydrogen
• Intermolecular coupling and fluxional behavior of hydrogen in phase IV
• Topological surface states in dense solid hydrogen
• High Temperature Raman analysis of Hydrogen Phase IV from Molecular Dynamics
• Semimetallic molecular hydrogen at pressure above 350 GPa
• GW space-time method: Energy band-gap of solid hydrogen
• Hydrogen phase-IV characterization by full account of quantum anharmonicity
• Experimental phase transition mapping for hydrogen above 300 K up to 300 GPa