ORCHID ESPEI datasets: literature and database-derived thermodynamic fitting inputs

Abstract

ORCHID ESPEI datasets: literature and database-derived thermodynamic fitting inputs: ESPEI 0.9.1 datasets built from the ORCHID literature values (ORCHID-Values) and from DFT, one folder per evidence class. Part of the ORCHID data release v2026.10. Status. Version 1, machine-extracted: values were read by language-model readers constrained to quote their source and checked automatically, and the release was then audited on the printed pages by adversarial audits, an independent second review of fit-facing records and a preliminary human review of a frozen sample. Flags such as accepted and ESPEI-ready record screening results, not certification; known issues are listed in the release notes. What 6,453 datasets with 12,513 values in 690 systems, in folders experimental/ (thermochemical and phase-composition ZPF tables; 1,118 datasets), invariants/ (ZPF from invariant-reaction tables; 1,546), model/ (values the papers calculated with a CALPHAD model, TDB SHA-256; 504) and dft/ (literature, mp, oqmd: HM_FORM of TDB phase endmembers mapped through the ORCHID phase registry; 3,285). Literature-derived values retain their ORCHID identifiers and source provenance and are screened against the literature release; direct MP and OQMD entries retain their database provenance and follow the corresponding DFT export rules. Uncertainties are in physical units (printed; ESPEI's experimental default where none was printed; DFT sigma calibrated against experiment, leave-system-out). Weights follow the exported uncertainty policy; unequal thermochemical uncertainties are represented by separate fitting records, and ZPF likelihood tolerances are not obtained by converting temperature uncertainties into thermochemical weights. Optional phase constraints, tagged and kept in their own folders (never mixed with measured data): derived/invariant-brackets/ and derived/liquid-stability/ (1,493 datasets) and assessed/ (assessed handbook phase-field points in each assessment's phase names; 643 datasets). Validated with ESPEI 0.9.1 check_dataset and load_datasets (VALIDATION.md); encoding fixes are counted there, literature records to correct are listed in UPSTREAM_CORRECTIONS.md. ESPEI validation checks the dataset format and loading behavior, while fitting suitability remains dependent on state identification, model-phase mapping and source quality. Limitations Version 1, machine-extracted literature values. Model-calculated values carry a method floor calibrated against experimental values of the same state, a lower bound of the model error because many models were fitted to those experiments: choose your own weight. 0 K DFT energies are used as 298.15 K enthalpies; DFT residuals are heavy-tailed. Use one DFT source per fit (different elemental references). Derived phase constraints encode the semantics of printed reactions; they are not measurements. Licence ORCHID's data are released under CC BY 4.0, as are the SGTE (B. Hallstedt, Calphad 89 (2025) 102833), Materials Project and OQMD data from which they are derived; attributions and statements of changes are in NOTICE.md, the licence of each folder in LICENSES.md (both in the bundle). The quotations from papers that accompany values are short excerpts kept for verification; they remain under the publishers' copyright and are not relicensed. Source papers, page images and full texts are not redistributed. The stated licence covers the ORCHID-produced content in this deposit; upstream data and software retain their documented terms and attribution requirements, and no publisher pages, handbook drawings or restricted TDB source files are included. Files: one zip (orchid-espei-v2026.10.zip) holding the files at their repository paths, a MANIFEST.sha256, the README, CHANGELOG and licence files. Its file list with sizes and SHA-256 is zenodo/espei.files.json in the data repository. How to cite R. Arróyave, J. Saal, D. Shin, ORCHID ESPEI datasets: literature and database-derived thermodynamic fitting inputs (version 2026.10; Version 1, machine-extracted), Zenodo (2026). https://doi.org/10.5281/zenodo.23735788 Part of: R. Arróyave, J. Saal, D. Shin, ORCHID data: umbrella record of the ORCHID datasets (version 2026.10; Version 1, machine-extracted), Zenodo (2026). https://doi.org/10.5281/zenodo.23736065 Also cite the original source of every value you use (each dataset's `reference` / `bibtex`, references.bib; index.csv lists the DOIs); A. Jain et al., The Materials Project: A materials genome approach to accelerating materials innovation, APL Materials 1 (2013) 011002, https://doi.org/10.1063/1.4812323 (CC BY 4.0); J. E. Saal et al., JOM 65 (2013) 1501, https://doi.org/10.1007/s11837-013-0755-4 and S. Kirklin et al., npj Comput. Mater. 1 (2015) 15010, https://doi.org/10.1038/npjcompumats.2015.10 (CC BY 4.0). @misc{orchid_espei_2026, author = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon}, title = {{ORCHID ESPEI datasets: literature and database-derived thermodynamic fitting inputs}}, version = {2026.10}, publisher = {Zenodo}, year = {2026}, doi = {10.5281/zenodo.23735788}, url = {https://doi.org/10.5281/zenodo.23735788}, note = {Version 1, machine-extracted} } @misc{orchid_data_2026, author = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon}, title = {{ORCHID data: umbrella record of the ORCHID datasets}}, version = {2026.10}, publisher = {Zenodo}, year = {2026}, doi = {10.5281/zenodo.23736065}, url = {https://doi.org/10.5281/zenodo.23736065}, note = {Version 1, machine-extracted} } Software and data citations These credits describe the ORCHID project and its examples. Cite the papers and software used in your analysis, together with the ORCHID release and original source of each observation. The list does not imply that every dataset was generated with every package. Preserve the versions and commit hashes recorded by each example; a repository link is not a reproducibility pin. Materials Project and OQMD energies retain separate references. pycalphad: Thermodynamic calculations and phase equilibria. R. Otis and Z.-K. Liu (2017), pycalphad: CALPHAD-based Computational Thermodynamics in Python (10.5334/jors.140). Repository. ESPEI: Thermodynamic parameter fitting and uncertainty quantification. B. Bocklund et al. (2019), ESPEI for efficient thermodynamic database development, modification, and uncertainty quantification: application to Cu–Mg (10.1557/mrc.2019.59). Repository. PhaseForge: MLIP-informed CALPHAD construction in the examples. S. Zhu, D. Sarıtürk, and R. Arróyave (2025), Machine learning potentials for alloys: a detailed workflow to predict phase diagrams and benchmark accuracy (10.1038/s41524-025-01814-z). Repository; archived software. PhaseForge+: Construction and experimental tuning of CALPHAD models in the examples; repository name PhaseForgePlus. C. Kunselman, S. Zhu, D. Sarıtürk, and R. Arróyave (2025), Construction and Tuning of CALPHAD Models Using Machine-Learned Interatomic Potentials and Experimental Data: A Case Study of the Pt–W System (10.1007/s11669-025-01222-2). Repository; archived software. Materials Project: DFT structures and energies; repository link is the API client, not the database itself. A. Jain et al. (2013), Commentary: The Materials Project: A materials genome approach to accelerating materials innovation (10.1063/1.4812323). Repository; data resource. OQMD: DFT structures and energies; qmpy is the supporting software. J. E. Saal et al. (2013), Materials Design and Discovery with High-Throughput Density Functional Theory: The Open Quantum Materials Database (OQMD) (10.1007/s11837-013-0755-4); S. Kirklin et al. (2015), The Open Quantum Materials Database (OQMD): assessing the accuracy of DFT formation energies (10.1038/npjcompumats.2015.10). Repository; data resource. Browse: orchid-project.org · data site data.orchid-project.org · source github.com/orchid-calphad/orchid-data. This work was supported by the U.S. National Science Foundation under awards OAC-2608825 and 2534344.