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MM: Fachverband Metall- und Materialphysik
MM 25: Development of Computational Methods: Crystal Structure and Properties
MM 25.5: Vortrag
Mittwoch, 29. März 2023, 11:15–11:30, SCH A 251
Sampling-free determination of accurate free energies: A bond lattice mean-field model for central potentials — •Raynol Dsouza1, Thomas Swinburne2, Liam Huber3, and Jörg Neugebauer1 — 1Max-Planck-Institut für Eisenforschung GmbH, 40237 Düsseldorf, Germany — 2CINaM, Campus de Luminy, 13288 Marseille, France — 3Grey Haven Solutions, Victoria, Canada
The computation of accurate anharmonic free energies at finite temperatures commonly involves the sampling of a large number of configurations. The commonly used (quasi)-harmonic approximation sacrifices physical fidelity by only sampling very few of these configurations. A recent study by the co-authors showed that a mean-field of a lattice of uncorrelated anharmonic first nearest-neighbour bonds can be used to approximate anharmonic free energies of fcc crystals with meV/atom accuracy when paired with a polarized bonding potential [1], thus recapturing an approximation of the anharmonic contributions with minimal computational expense. We extend this approach to central potentials, while maintaining the original constraints of material compatibility and thermodynamic self-consistency of the model. Using a parameterized bonding potential generated from a few T=0 K ab initio calculations [2] for fcc aluminium, we show that the model yields free energies close to meV/atom of those calculated from ab initio thermodynamic integration for a fraction of the computational effort. [1] Swinburne et al., Phys. Rev. B 102, 100101(R) (2020) [2] Glensk et al., Phys. Rev. Lett. 114, 195901 (2015)