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MM: Fachverband Metall- und Materialphysik

MM 35: Computational Materials Modelling - Phonons & Phase Stability

MM 35.2: Vortrag

Mittwoch, 13. März 2013, 12:00–12:15, H24

Ab initio finite temperature description of α Ti including anharmonic contributions — •Dominique Korbmacher, Albert Glensk, Blazej Grabowski, and Jörg Neugebauer — Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany

Ti and its alloys are technologically relevant for instance for aircraft or medical applications. Ab initio methods based on density-functional theory (DFT) are now routinely used to investigate T=0 K properties such as, e.g., the influence of alloying elements on titanium’s mechanical properties. In contrast, finite temperature DFT studies are rare and, in particular, limited to approximations such as the quasiharmonic model. While the latter is an accurate approximation for many elements, deviations of ≈15% are found for the heat capacity of α Ti (hcp) at higher temperatures [1].

In the present study, we investigate the influence of anharmonic excitations on the thermodynamics of α Ti. To overcome long CPU times we use here the recently developed UP-TILD method [2], a coarse graining scheme allowing to reduce the computation time significantly while keeping high accuracy. In the talk we present the contribution of anharmonicity to various thermodynamic quantities of α Ti and discuss its balance with respect to the other finite temperature excitations. Finally, we reveal whether it can account for the observed discrepancy with experiment or whether the problem originates from an inherent shortcoming of the employed DFT functionals.

[1] Z. G. Mei et al., PRB 80, 104116 (2009).

[2] B. Grabowski et al., PRB 79, 134106 (2009).