Regensburg 2013 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 35: Computational Materials Modelling - Phonons & Phase Stability

MM 35.1: Vortrag

Mittwoch, 13. März 2013, 11:45–12:00, H24

Phonon dispersions in iron: comparing empirical potentials with first-principles calculations and experimental results — •Daniele Dragoni¹, Davide Ceresoli², and Nicola Marzari¹ — ¹École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland — ²Consiglio Nazionale delle Ricerche, Milano, Italy

Many empirical potentials for iron and its alloys are available in literature. Their performance and reliability has been tested for energetics, thermodynamic properties, and relative bcc-fcc stability under martensitic transformation (Bain path). We focus here on phonon dispersions as a robust indicator of potentials’ quality. Both the low temperature bcc phase (ferromagnetic α-phase up to 1043 K, and paramagnetic β-phase up to 1184 K) and the higher temperature fcc paramagnetic γ-phase (between 1184 K and 1670 K) are considered and compared to experimental results and, where available, to ab-initio data. This approach provides valuable insight about the relative accuracy of potentials in treating long- and short-wavelength vibrations and elastic constants at different temperatures and for distinct solid phases.