Liquid-liquid phase transition in hydrogen by coupled electron-ion Monte Carlo simulations

Carlo Pierleoni, Miguel A. Morales, Giovanni Rillo, Markus Holzmann, David M. Ceperley

Research output: Contribution to journalArticlepeer-review


The phase diagram of high-pressure hydrogen is of great interest for fundamental research, planetary physics, and energy applications. A first-order phase transition in the fluid phase between a molecular insulating fluid and a monoatomic metallic fluid has been predicted. The existence and precise location of the transition line is relevant for planetary models. Recent experiments reported contrasting results about the location of the transition. Theoretical results based on density functional theory are also very scattered. We report highly accurate coupled electron-ion Monte Carlo calculations of this transition, finding results that lie between the two experimental predictions, close to that measured in diamond anvil cell experiments but at 25-30 GPa higher pressure. The transition along an isotherm is signaled by a discontinuity in the specific volume, a sudden dissociation of the molecules, a jump in electrical conductivity, and loss of electron localization.

Original languageEnglish (US)
Pages (from-to)4953-4957
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number18
StatePublished - May 3 2016


  • High pressure
  • Hydrogen metallization
  • Molecular dissociation
  • Phase transitions
  • Quantum Monte Carlo

ASJC Scopus subject areas

  • General


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