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MM: Fachverband Metall- und Materialphysik

MM 37: Computational Materials Modelling V - Point defects

MM 37.4: Vortrag

Mittwoch, 2. April 2014, 11:00–11:15, IFW D

Vacancies in fcc metals — •Mostafa Mortazavifar and Martin Oettel — Institut für Angewandte Physik, Eberhard Karls Universität Tübingen, Tübingen, Germany

Through a cluster expansion of the crystal partition function, we derive an approximate expression for the equilibrium concentration of thermal vacancies in solids which allows for a transparent interpretation of the vacancy volume and the energetic/entropic part in the corresponding Gibbs energy of vacancy formation Δ G_v. For the text–book model crystals made of hard spheres and Lennard–Jones particles very good agreement with simulation data is found. Application to Ni through the embedded–atom method (EAM) reveals a strong sensitivity of the variation of Δ G_v with temperature to details of the EAM potential [1]. We propose to use our formula for Δ G_v(T) in reference calculations where the needed partition function terms should be evaluated by quantum density functional theory (qDFT). The results can be employed in theoretical materials science using ab-initio methods or in constructing effective classical potentials.

[1] M. Mortazavifar and M. Oettel, Thermal vacancies in close–packing solids, arXiv:1311.5093 [cond-mat.soft]