Calculation update! New properties have been added to the website for dislocation monopole core structures, dynamic relaxes of both crystal and liquid phases, and melting temperatures! Currently, the results for these properties predominately focus on EAM-style potentials, but the results will be updated for other potentials as the associated calculations finish. Feel free to give us feedback on the new properties so we can improve their representations as needed.
Warning! Note that elemental potentials taken from alloy descriptions may not work well for the pure species. This is particularly true if the elements were fit for compounds instead of being optimized separately. As with all interatomic potentials, please check to make sure that the performance is adequate for your problem.
Citation: E. Ţurcan, L. La Rosa, D. Fioravanti, and F. Maresca (2026), "Towards DFT-accurate prediction of twin interface structure and motion in NiTi shape memory alloys", Acta Materialia303, 121651. DOI: 10.1016/j.actamat.2025.121651.
Abstract: Recent atomistic simulations have suggested that twin boundary motion, rather than interface energy, governs twin formation in NiTi shape memory alloys (SMAs). Yet, these findings rely on empirical interatomic potentials (IAPs), whose intrinsic inaccuracies pose uncertainties regarding the quantitative prediction of interface energetics, driving force and transformation mechanisms. In this study, we address these limitations by developing a machine learning IAP using the Performant Atomic Cluster Expansion (PACE) framework, trained on a comprehensive database of density functional theory (DFT) calculations. The resulting PACE-IAP outperforms state-of-the-art empirical and neural network-based potentials, by reproducing accurate lattice parameters, improved elastic constants, and correct features of the B2-B19' phase transformation. Leveraging this increased accuracy, we model the structure, energetics, and motion of twin interfaces in NiTi. By computing the extrapolation grade, we verify that the local atomic environments at the predicted interfaces are well contained within the DFT configurational space. Our simulations confirm that the driving force for twin boundary motion, rather than the interface energy, controls the hierarchy of twin formation in NiTi. These atomistic insights can be used into mesoscale models of microstructural formation, ultimately enhancing predictions of variant selection and enabling the design of high-performance SMAs.