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Physics of the Earth and Planetary Interiors 139 (2003) 243253 The particle-in-cell model for ab initio thermodynamics
 

Summary: Physics of the Earth and Planetary Interiors 139 (2003) 243­253
The particle-in-cell model for ab initio thermodynamics:
implications for the elastic anisotropy
of the Earth's inner core
C.M.S. Gannarellia, D. Alfèa,b, M.J. Gillana,
a Physics and Astronomy Department, University College London, Gower Street, London WC1E 6BT, UK
b Research School of Geological and Geophysical Sciences, Birkbeck and University College London,
Gower Street, London WC1E 6BT, UK
Received 17 February 2003; received in revised form 1 September 2003; accepted 2 September 2003
Abstract
We assess the quantitative accuracy of the particle-in-cell (PIC) approximation used in recent ab initio predictions of the
thermodynamic properties of hexagonal-close-packed (hcp) iron at the conditions of the Earth's inner core. The assessment is
made by comparing PIC predictions for a range of thermodynamic properties with the results of more exact calculations that
avoid the PIC approximation. It is shown that PIC gives very accurate results for some properties, but that it gives an unreliable
treatment of anharmonic lattice vibrations. In addition, our assessment does not support recent PIC-based predictions that
the hexagonal c/a ratio increases strongly with increasing temperature, and we point out that this casts doubt on a proposed
re-interpretation of the elastic anisotropy of the inner core.
© 2003 Elsevier B.V. All rights reserved.
PACS: 62.20.D; 62.50.+p; 71.15.Ap; 91.35.-x
Keywords: Ab initio; Anisotropy; Core; Thermodynamics

  

Source: Alfè, Dario - Departments of Earth Sciences & Physics and Astronomy, University College London
Gannarelli, Ché - Department of Physics and Astronomy, University College London

 

Collections: Geosciences; Materials Science; Physics