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First-principles-based calculations of temperature-dependent thermodynamic properties of intermetallic compounds

Mauro Palumbo, Ruhr-Universität Bochum, Bochum, Germany

Suzana Fries, Ruhr-Universität Bochum, Bochum, Germany

Alain Pasturel, , Saint-Martin d’Hères, France

Dario Alfe, University College London, London, United Kingdom

Time & Place
  • Date: 07.09.2014
  • Time:
  • Place: TOFA 2014, Brno, Czech Republic

Abstract

Nowadays, DFT-based calculations are a standard tool to obtain different physical properties of materials. Their use in thermodynamic modelling has proven useful in several cases, as shown for example in our previous works1-3. However, in most cases these calculations are limited to 0 K. Although several DFT-based techniques are available to go beyond ground-state calculations, they usually require an additional theoretical and computational effort. For this reason, studies of temperature-dependent effects are more limited to date.

In this work we have computed phonon frequencies in the harmonic approximation using the small displacement method and the PHON code4 for two selected intermetallic compounds of the family of Topologically Close Packed (TCP) phases. Mechanical instability has been found in some of the investigated configurations. We have analysed the importance of anharmonic contributions using thermodynamic integration based on Ab Initio Molecular Dynamics (AIMD)5. The importance of the present results for chemical disorder and thermodynamic modelling at high temperature is finally discussed.

References:

1. M. Palumbo, T. Abe, C. Kocer, H. Murakami, H. Onodera, CALPHAD, 34 (2010) 494
2. M. Palumbo, T. Abe, S. G. Fries, A. Pasturel, Phys. Rev. B, 83 (2011) 144109
3. M. Palumbo, S. G. Fries, T. Hammerschmidt, T. Abe, J.-C. Crivello, A. Breidi, J-.M. Joubert, R. Drautz, Computational Materials Science, 81 (2014) 433
4. D. Alfè, Computer Physics Communications 180, (2009) 2622
5. M. Palumbo, S. G. Fries, A. Pasturel, D. Alfè, Journal of Chemical Physics, accepted

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