Equation of state of hexagonal closed packed iron under Earth’s core conditions from quantum Monte Carlo calculations

E. Sola, J. P. Brodholt, and D. Alfè
Phys. Rev. B 79, 024107 – Published 13 January 2009

Abstract

We applied quantum Monte Carlo techniques to compute the equation of state of hexagonal closed packed iron in the range of pressure relevant to Earth’s core. We used an accurate iron pseudopotential with a frozen Ne core. Trial wave functions have been obtained from density-functional theory (DFT) plane-wave calculations and expanded in systematically improvable B splines. Tests with various exchange-correlation functionals showed that the B3LYP functional is the one that provided the best trial wave functions. Diffusion Monte Carlo calculations were carried out using simulation cells with up to 96 atoms (1536 electrons), with some attempts to use up to 150 atoms, and corrected for finite-size errors using the scheme of Chiesa et al. [Phys. Rev. Lett. 97, 076404 (2006)] and Kwee et al. [Phys. Rev. Lett. 100, 126404 (2008)]. The calculated equation of state agrees closely with the experiments of Mao et al. [J. Geophys. Res. 95, 21737 (1990)] and those of Dewaele et al. [Phys. Rev. Lett. 97, 215504 (2006)]. It also agrees with the DFT data of Söderlind et al. [Phys. Rev. B 53, 14063 (1996)] and Alfè et al. [Phys. Rev. B 61, 132 (2000)], and therefore, reinforces those previous calculations.

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  • Received 4 November 2008

DOI:https://doi.org/10.1103/PhysRevB.79.024107

©2009 American Physical Society

Authors & Affiliations

E. Sola1,2, J. P. Brodholt1,2, and D. Alfè1,2,3,4

  • 1Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, United Kingdom
  • 2Materials Simulation Laboratory, University College London, Gower Street, London WC1E 6BT, United Kingdom
  • 3Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
  • 4London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, United Kingdom

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Issue

Vol. 79, Iss. 2 — 1 January 2009

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