Edinburgh Research Explorer

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

Research output: Contribution to journalArticle

  • Alexander F. Goncharov
  • John S. Tse
  • Hui Wang
  • Jianjun Yang
  • Viktor V. Struzhkin
  • Ross T. Howie
  • Eugene Gregoryanz

Related Edinburgh Organisations

Original languageEnglish
Article number024101
Number of pages8
JournalPhysical Review B: Condensed Matter and Materials Physics
Volume87
Issue number2
DOIs
Publication statusPublished - 1 Jan 2013

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 graphenelike) 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 exhibits a new interstitial valence charge bonding scheme.

ID: 5995616