Structure and vibrational properties of methane up to 71 GPa

Maxim Bykov, Elena Bykova, Chris J. Pickard, Miguel Martinez-Canales, Konstantin Glazyrin, Jesse S. Smith, Alexander F. Goncharov

Research output: Contribution to journalArticlepeer-review

Abstract

Single-crystal synchrotron X-ray diffraction, Raman spectroscopy, and first principles calculations have been used to identify the structure of the high-pressure (HP) phase of molecular methane above 20 GPa up to 71 GPa. The structure of HP phase is trigonal R3, which can be represented as a distortion of the cubic phase B, previously documented at 7-15 GPa and confirmed here. The positions of hydrogen atoms in HP phase have been 19 obtained from first principles calculations. The molecules occupy four different crystallographic sites in phases B and eleven sites in the HP phase, which result in splitting of molecular stretching modes detected in Raman spectroscopy and assigned here based on 22 a good agreement with the Raman spectra calculated from the first principles.
Original languageEnglish
JournalPhysical Review B
Publication statusAccepted/In press - 25 Oct 2021

Keywords

  • cond-mat.mtrl-sci
  • physics.chem-ph

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