Optical properties of high-pressure fluid hydrogen across molecular dissociation

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

Research output: Contribution to journalArticlepeer-review


Optical properties of compressed fluid hydrogen in the region where dissociation and metallization is observed are computed by ab initio methods and compared with recent experimental results. We confirm that at T > 3,000 K, both processes are continuous, while at T < 1,500 K, the first-order phase transition is accompanied by a discontinuity of the dc conductivity and the thermal conductivity, while both the reflectivity and absorption coefficient vary rapidly but continuously. Our results support the recent analysis of National Ignition Facility (NIF) experiments [Celliers PM, et al. (2018) Science 361:677–682], which assigned the inception of metallization to pressures where the reflectivity is ∼0.3. Our results also support the conclusion that the temperature plateau seen in laser-heated diamond-anvil cell (DAC) experiments at temperatures higher than 1,500 K corresponds to the onset of optical absorption, not to the phase transition.

Original languageEnglish (US)
Pages (from-to)9770-9774
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number20
StatePublished - May 14 2019


  • High pressure
  • Hydrogen
  • Metal insulator
  • Optical properties
  • Quantum Monte Carlo

ASJC Scopus subject areas

  • General


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