Lithium hydroxide, LiOH, at elevated densities

Andreas Hermann*, N. W. Ashcroft, Roald Hoffmann

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We discuss the high-pressure phases of crystalline lithium hydroxide, LiOH. Using first-principles calculations, and assisted by evolutionary structure searches, we reproduce the experimentally known phase transition under pressure, but we suggest that the high-pressure phase LiOH-III be assigned to a new hydrogen-bonded tetragonal structure type that is unique amongst alkali hydroxides. LiOH is at the intersection of both ionic and hydrogen bonding, and we examine the various ensuing structural features and their energetic driving mechanisms. At P = 17 GPa, we predict another phase transition to a new phase, Pbcm-LiOH-IV, which we find to be stable over a wide pressure range. Eventually, at extremely high pressures of 1100 GPa, the ground state of LiOH is predicted to become a polymeric structure with an unusual graphitic oxygen-hydrogen net. However, because of its ionic character, the anticipated metallization of LiOH is much delayed; in fact, its electronic band gap increases monotonically into the TPa pressure range. (C) 2014 AIP Publishing LLC.

Original languageEnglish
Article number024505
Number of pages11
JournalThe Journal of Chemical Physics
Volume141
Issue number2
DOIs
Publication statusPublished - 9 Jul 2014

Keywords

  • TEMPERATURE PHASE-TRANSITION
  • NEUTRON POWDER DIFFRACTION
  • HIGH-PRESSURE
  • AB-INITIO
  • CRYSTAL-STRUCTURE
  • BONDING CONDITIONS
  • ELECTRON-DENSITY
  • CARBON-DIOXIDE
  • HYDROGEN
  • NAOH

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