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Free energies of iron phases at high pressure and temperature: Molecular dynamics study

Anatoly B. Belonoshko, Jie Fu, and Grigory Smirnov
Phys. Rev. B 104, 104103 – Published 9 September 2021; Erratum Phys. Rev. B 105, 059903 (2022)

Abstract

The crystal structure of iron, the major component of the Earth's inner core (IC), is unknown under the IC high pressure (P) (3.3–3.6 Mbar) and temperature (T) (5000–7000 K). Experimental and theoretical data on the phase diagram of iron at these extreme PT conditions are contradictory. Applying quasi-ab initio and ab initio molecular dynamics we computed free energies of the body-centered cubic (bcc), hexagonal close-packed (hcp), and liquid phases. The ionic free energies, computed for the embedded-atom model, were corrected for electronic entropy. Such correction brings the melting temperatures of the hcp iron in very good agreement with previous ab initio data. This validates the calculation of the bcc phase, where fully ab initio treatment is not technically possible due to large sizes required for convergence. The resulting phase diagram shows stabilization of the bcc phase prior to melting in the pressure range of the IC. The melting temperature of the bcc phase is equal to 7190 K at the pressure 360 GPa.

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  • Received 10 June 2021
  • Accepted 25 August 2021

DOI:https://doi.org/10.1103/PhysRevB.104.104103

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by Bibsam.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Erratum

Authors & Affiliations

Anatoly B. Belonoshko1,2, Jie Fu3, and Grigory Smirnov2,4

  • 1Condensed Matter Theory, Department of Physics, AlbaNova University Center, Royal Institute of Technology (KTH), 10691 Stockholm, Sweden
  • 2National Research University Higher School of Economics, 123458 Moscow, Russia
  • 3Department of Physics, School of Physical Science and Technology, Ningbo University, 315211 Ningbo, China
  • 4Joint Institute for High Temperatures of the Russian Academy of Sciences, 125412 Moscow, Russia

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Issue

Vol. 104, Iss. 10 — 1 September 2021

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