# ORCHID

> Open Repository for CALPHAD Hypotheses, Intelligence, and Discovery (Texas A&M University). Openly licensed CALPHAD
> thermodynamic databases (TDB), binary convex hulls (DFT and CALPHAD), calculated binary phase diagrams and
> phase-equilibrium and thermochemical values read from published papers. Every value carries its source, licence and
> evidence class.

Status of the data release v2026.10: 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 (https://orchid-project.org/#releases).

Evidence classes are never mixed: experimental | model (linked to the exact TDB file by SHA-256) | dft | assessed_phase_diagram.

## Data
- [Catalog (JSON)](https://orchid-project.org/data/catalog.json): one record per database: name, elements, phases, tier, licence, source URL.
- [Catalog (CSV)](https://orchid-project.org/data/catalog.csv)
- [Bundled TDB files](https://github.com/orchid-calphad/orchid-project.org/tree/main/data/databases): redistributable databases; licences in data/NOTICE.md.
- [DFT hulls, Materials Project v2026.04.13](https://github.com/orchid-calphad/orchid-project.org/tree/main/data/hulls/dft-mp): one JSON per binary system, interval schema.
- [DFT hulls, OQMD v1.8](https://github.com/orchid-calphad/orchid-project.org/tree/main/data/hulls/dft-oqmd): same schema; fitted elemental references (not comparable in energy to MP).
- [CALPHAD hulls, SGTE](https://github.com/orchid-calphad/orchid-project.org/tree/main/data/hulls/calphad-sgte)
- [Literature data, all records (CSV.gz)](https://orchid-project.org/data/literature/orchid-literature.csv.gz): invariant reactions, transitions, phase compositions, thermochemical and structural values from published papers; evidence class, units, T (K) and pressure, phases and compositions (mole fraction), method, conditions, citation + DOI, verbatim quote + page, flags. Nested fields are JSON strings.
- [Literature data (JSONL.gz)](https://orchid-project.org/data/literature/orchid-literature.jsonl.gz): same records, one JSON object per line.
- [Literature data per system](https://orchid-project.org/data/literature/index.json): index of data/literature/systems/<SYS>.json (SYS = sorted uppercase elements joined by '-', e.g. AL-NI).
- [Literature papers](https://orchid-project.org/data/literature/papers.json) and [experimental contexts](https://orchid-project.org/data/literature/contexts.json); field reference: [SCHEMA.md](https://orchid-project.org/data/literature/SCHEMA.md); about: https://orchid-project.org/dataset/
- [DFT vs experiment, formation enthalpies (JSON)](https://orchid-project.org/data/literature/dft_parity.json): literature HM_FORM values (kJ/mol-atom) paired with the lowest-energy Materials Project and OQMD entry at the same binary composition (separate sources, never averaged); matching rules, exclusions, per-source MAE/RMSE/r. Viewer: https://orchid-project.org/dft-parity/
- [Phase registry (JSON)](https://data.orchid-project.org/phases/registry.json): compact index, one row per (binary system, phase) (id, names, structure tier and prototype, counts); full records (models with tdb_definition, stability, references) in https://data.orchid-project.org/phases/systems/<SYS>.json, id phase:<sorted lower-case elements>:<slug>; every name (tdb:<file>:<NAME>, paper:<doi>:<label>, corpus:<id>, mp:<id>, oqmd:<id>), CALPHAD models (TDB SHA-256, sublattices), stability in the calculated diagrams, literature value counts, up to 10 example references (DOI, role). Structure type: tier A standard phase name, tier B unique Materials Project + OQMD on-hull match ("DFT-supported"), tier C assessment-declared (one consistent structure in the Hallstedt 2025 crystallographic table, assessor-stated); otherwise candidates and status needs_review. Each TDB model has tdb_definition: verbatim PHASE/CONSTITUENT/TYPE_DEFINITION statements with line numbers, parsed sublattices/constituents/magnetic model, parameter counts. Also [CSV](https://data.orchid-project.org/phases/registry.csv), [JSON-LD](https://data.orchid-project.org/phases/registry.jsonld), [structure types](https://data.orchid-project.org/phases/structure_types.json), [review queue](https://data.orchid-project.org/phases/review_queue.json), [schema](https://data.orchid-project.org/phases/SCHEMA.md). Static pages (no JavaScript): https://data.orchid-project.org/phases/pages/index.html, per system https://data.orchid-project.org/phases/pages/<SYS>.md (also .html); structure types also as https://data.orchid-project.org/phases/structure_types.parquet. Browser: https://orchid-project.org/phases/
- [Assessed phase assemblages](https://data.orchid-project.org/assessed-phase-assemblages/README.md): one (T, x, P) point deep inside each named phase field of expert-drawn (assessed) binary diagrams (Okamoto's Desk Handbook), evidence class assessed_phase_diagram; https://data.orchid-project.org/assessed-phase-assemblages/records.parquet (also .jsonl.gz, .csv), ESPEI ZPF datasets, fields in SCHEMA.md.
- [ORCHID ESPEI datasets](https://data.orchid-project.org/espei/README.md): ESPEI 0.9.1 JSON per evidence class (experimental/, model/, invariants/, dft/literature, dft/mp, dft/oqmd), every value with its ORCHID observation id, source DOI, uncertainty and ESPEI weight; one row per dataset in https://data.orchid-project.org/espei/index.csv; validation https://data.orchid-project.org/espei/VALIDATION.md; DFT sigma calibration https://data.orchid-project.org/espei/dft/CALIBRATION.md.
- [Bibliography](https://data.orchid-project.org/bibliography/README.md): every paper ORCHID knows (read, cited as original sources, behind TDB files and assessed diagrams, discovery leads) with Crossref metadata, roles, evidence counts and typed relations; tables https://data.orchid-project.org/bibliography/papers.parquet and https://data.orchid-project.org/bibliography/edges.parquet; one paper https://data.orchid-project.org/bibliography/papers/<key>.json (key lookup in bibliography/index.json); one system https://data.orchid-project.org/bibliography/systems/<SYS>.json; static pages https://data.orchid-project.org/bibliography/pages/index.html; DOIs matched from printed references are checked against Crossref (doi_match; dropped mismatches in bibliography/DOI_MISMATCHES.md).
- [Croissant metadata](https://orchid-project.org/data/croissant.json)

## Static data pages (no JavaScript; data.orchid-project.org)
- [Data site guide](https://data.orchid-project.org/llms.txt) and [all systems with one-line summaries](https://data.orchid-project.org/llms-full.txt)
- Per chemical system: https://data.orchid-project.org/systems/<SYS>.md (also .html and .csv; SYS = sorted uppercase elements joined by '-', e.g. AL-NI): summary, calculated phase diagrams (TDB + SHA-256), invariant reactions, formation enthalpies with DFT comparison, other properties, each value with source, DOI, page and quote.
- Per compound: https://data.orchid-project.org/compounds/<FORMULA>.md (reduced formula, e.g. Al3Ni): literature formation enthalpies vs Materials Project and OQMD.
- Indexes: [systems](https://data.orchid-project.org/systems/index.md), [compounds](https://data.orchid-project.org/compounds/index.md), [reporting papers](https://data.orchid-project.org/papers/index.md)
- Sitemaps: https://orchid-project.org/sitemap.xml, https://data.orchid-project.org/sitemap.xml

## Site pages
- [Data explorer](https://orchid-project.org/data-explorer/) · [Catalog](https://orchid-project.org/catalog/) · [Phase diagrams](https://orchid-project.org/phase-diagrams/) · [Phases](https://orchid-project.org/phases/) · [Bibliography](https://data.orchid-project.org/bibliography/pages/index.html) · [Hulls](https://orchid-project.org/catalog/binary-thermo.html) · [Data](https://orchid-project.org/dataset/) · [DFT vs experiment](https://orchid-project.org/dft-parity/) · [Contribute](https://orchid-project.org/contribute/)

## About
- [About ORCHID](https://orchid-project.org/about/): mission, contents, how the data are built, team (R. Arróyave, Texas A&M University; J. Saal, Citrine Informatics; D. Shin, Oak Ridge National Laboratory), licensing and how to cite.
- [How ORCHID is built](https://orchid-project.org/workflow/): the workflow in eight stages (sources, locating artifacts, reading with quoted values, deterministic gates, evidence classes, derived products, releases, validation), each linked to its code in https://github.com/orchid-calphad/orchid-pipeline (map: WORKFLOW.md); a synthetic demo that runs without papers or API keys; the benchmark and the MCP server.

## Notes
- Funding: This work was supported by the U.S. National Science Foundation under awards OAC-2608825 and 2534344.
- DFT layers carry formation enthalpy only; reference kinds differ between sources and must not be averaged.
- Literature data: derived data CC BY 4.0 (cite ORCHID and each value's source paper); each quote is a short excerpt kept for verification, under the publishers' copyright (not relicensed); source papers are not redistributed. Use only records with flags.extraction_accepted = true unless you handle disputes; uncertainty with basis stated_default is a placeholder, not a measurement.
- Files we may not redistribute are listed in the catalog with links to their original sources only.
- Cite releases by their Zenodo DOI; see CITATION.cff. Release v2026.10 is eight datasets plus an umbrella record (cite the dataset you use and the umbrella):
  - ORCHID data: umbrella record of the ORCHID datasets: https://doi.org/10.5281/zenodo.23736065
  - ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature: https://doi.org/10.5281/zenodo.23735569
  - ORCHID-Diagrams: calculated binary phase diagrams: https://doi.org/10.5281/zenodo.23735859
  - ORCHID-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD): https://doi.org/10.5281/zenodo.23735891
  - ORCHID-Parity: DFT-vs-experiment formation-enthalpy benchmark: https://doi.org/10.5281/zenodo.23735943
  - ORCHID-Registry: phase registry of binary systems: https://doi.org/10.5281/zenodo.23735970
  - ORCHID-Assemblages: assessed phase assemblages of binary systems: https://doi.org/10.5281/zenodo.23735996
  - ORCHID ESPEI datasets: literature and database-derived thermodynamic fitting inputs: https://doi.org/10.5281/zenodo.23735788
  - ORCHID-Bibliography: papers and typed citation relations: https://doi.org/10.5281/zenodo.23736021
- Every data JSON carries a top-level cite_as object (text, BibTeX, DOI); Parquet files carry orchid.cite_as key-value metadata; data/literature/CITATION.txt sits beside the CSV.