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Melting curve of tantalum from first principles S. Taioli,1 C. Cazorla,2,3 M. J. Gillan,2,3 and D. Alf1,2,3
 

Summary: Melting curve of tantalum from first principles
S. Taioli,1 C. Cazorla,2,3 M. J. Gillan,2,3 and D. Alfè1,2,3
1Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, United Kingdom
2Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
3
London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT, United Kingdom
Received 2 February 2007; revised manuscript received 28 March 2007; published 5 June 2007
We report on the first-principles calculation of the melting curve of Ta in the pressure range 0­300 GPa. The
calculations have been performed using density functional theory DFT with generalized gradient corrections
and the projector augmented wave method. The melting curve has been evaluated using the method of the
coexistence of phases, with the help of an auxiliary reference potential. The melting curve obtained with the
reference potential has then been corrected using free energy differences between the DFT and the reference
potential, so as to obtain the DFT melting curve. The results are in good agreement with diamond anvil cell
experiments at low pressure, but they rapidly diverge from these as pressure is increased, and agree well with
shock-wave experiments at high pressure. A general description of the lattice dynamics and thermal properties
of body-centered cubic tantalum using DFT is also presented. The equation of state at zero temperature and the
phonon dispersion are investigated using both the local density approximation and the generalized gradient
approximation GGA . Good agreement with the zero-temperature equation of state and zero-pressure phonon
dispersions is obtained with the GGA. This agreement reinforces the reliability of the calculated melting curve.
DOI: 10.1103/PhysRevB.75.214103 PACS number s : 61.20.Ja, 71.15.Pd, 71.22. i, 64.70.Dv

  

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

 

Collections: Physics; Geosciences