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MM: Fachverband Metall- und Materialphysik

MM 10: Poster Session 1

MM 10.28: Poster

Montag, 5. September 2022, 18:00–20:00, P2

Recent progress in ICET — J. Magnus Rahm, •Erik Fransson, Pernilla Ekborg-Tanner, Joakim Brorsson, Mattias Ångqvist, and Paul Erhart — Department of Physics, Chalmers University of Technology, Gothenburg, Sweden

Alloy cluster expansions (CEs) provide an accurate and computationally efficient mapping of the potential energy surface of multi-component systems that enables comprehensive sampling of the many-dimensional configuration space. In this contribution, we provide an update regarding recent developments and new features in the integrated cluster expansion toolkit (ICET). We have implemented a version of the constituent strain formalism in ICET, which enables treatment of long-ranged strain contributions. This approach is demonstrated for the Pd-H system in order to study coherent phase transitions via constrained Monte Carlo simulations. Furtermore, in CEs of low-dimensional systems, lack of symmetry leads to large numbers of independent effective cluster interactions (ECIs). We have made it possible to merge orbits, i.e., reduce the number of independent ECIs by considering local symmetries and merging parameters that are similar. This approach enables training of accurate models while requiring significantly fewer DFT calculations. This approach is employed to study surface segregation in AuPd and CuPd in environments ranging from vacuum to high pressures of hydrogen. Finally, we have added a number of additional features, including Wang-Landau sampling and extraction of long-range order parameters, and the code has undergone a thorough review that has resulted in a significant performance boost.