Dresden 2026 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 19: Poster Session

MM 19.4: Poster

Dienstag, 10. März 2026, 18:00–20:00, P5

Unveiling Anharmonicity in High-temperature Diffusion Through Transition State Thermodynamic Integration — •Wenchuan Liu¹, Xi Zhang¹, Xu Xiang¹, Sergiy Divinski², and Blazej Grabowski¹ — ¹Institute for Materials Science, University of Stuttgart, D-70569 Stuttgart, Germany — ²Institute of Materials Physics, University of Münster, 48149 Münster, Germany

Accurate modeling of high-temperature atomic diffusion requires a full treatment of thermal effects, particularly anharmonic lattice vibrations, which are often oversimplified in density functional theory (DFT)-based descriptions. We introduce a novel ab initio method, transition state thermodynamic integration (TSTI), that explicitly incorporates anharmonic contributions to vacancy migration Gibbs energies. TSTI combines DFT, molecular dynamics, and machine-learning interatomic potentials within a unified ab initio framework. Applied first to BCC tungsten, the method quantitatively captures non-Arrhenius diffusivities arising from anharmonicity. We further demonstrate its general applicability to metastable HCP aluminum, enabling high-fidelity input for CALPHAD-type mobility modeling. TSTI provides a general route to computing high-temperature diffusivities with DFT accuracy.

Keywords: transition state thermodynamic integration; molecular dynamics; machine-learning interatomic potentials; diffusion