Hea Bench MCP Server

hea-bench

Open, interpretable tools for computing the standard high-entropy-alloy (HEA) and high-entropy-oxide (HEO) thermodynamic and geometric descriptors and the classic empirical phase-prediction rules — from any composition, with no fitted model and no black box. Every number is a transparent closed-form expression over a curated element-property table, validated against the primary literature.

Try it now: https://dfieser.github.io/hea-bench/ — no install, runs entirely in your browser.

Using an AI coding agent to integrate this? See AGENTS.md for a machine-oriented guide to the API, exact return types and units, the fastest path to each task, and the mistakes to avoid.

What it computes

For any composition it reports:

• Core descriptors — mixing entropy ΔSmix, atomic-size mismatch δ, mean melting temperature Tm, Miedema mixing enthalpy ΔHmix, valence-electron concentration VEC, Yang–Zhang Ω, Pauling electronegativity mismatch Δχ, Mansoori excess entropy SE, ΔGss, ΔGmax, King Φ, Ye φ.
• Phase-prediction rules — Yeh entropy, Zhang δ, Guo–Liu VEC, Yang–Zhang Ω, King Φ, Ye φ.
• Miedema formation enthalpies (browser/desktop apps) — compound / solid-solution / amorphous, decomposed into chemical, elastic, structural, and topological terms.
• High-entropy oxides (hea_bench.oxides + the apps' Oxides mode) — rock-salt, perovskite, fluorite, and pyrochlore formability descriptors over Shannon ionic radii with automatic charge-balance oxidation-state assignment: per-sublattice configurational entropy, cation size disorder, Goldschmidt t / octahedral μ / Bartel τ, the fluorite radius-dispersion rule, and the pyrochlore radius-ratio window.

Element coverage: 37 elements for alloys (Ag Al Au Be Ca Ce Co Cr Cu Fe Gd Hf In Ir La Li Mg Mn Mo Nb Ni Os Pd Pt Re Rh Ru Sc Si Sn Ta Ti V W Y Zn Zr); the Miedema pair table covers 75; the oxide module's Shannon table covers 94.

Four ways to run it

The three surfaces share one calculation core. The browser/desktop core (web/hea-calculator-core.js) is a pure-JS port of the Python library, and tests/test_web_parity.py guarantees the two match on all 666 binary pairs and the canonical multi-element fixtures, while tests/test_web_oxides_parity.py does the same for the oxide module, down to identical warning messages.

Quick start (Python)

pip install hea-bench

import hea_bench as hb

cantor = {"Co": 0.2, "Cr": 0.2, "Fe": 0.2, "Mn": 0.2, "Ni": 0.2}

hb.smix(cantor)               # 13.381 J/(mol·K)  = R · ln 5
hb.delta(cantor)              # 3.164 % atomic-size mismatch
hb.vec(cantor)                # 8.0 valence electrons
hb.mixing_enthalpy(cantor)    # -4.16 kJ/mol  (Miedema)
hb.omega(cantor)              # 5.79  (Yang–Zhang)
hb.delta_chi(cantor)          # 0.138 Pauling electronegativity mismatch
hb.s_excess(cantor)           # 0.318 J/(mol·K)  (Mansoori excess entropy)
hb.delta_g_max(cantor)        # -8.00 kJ/mol  (most-negative Miedema pair)
hb.phi_king(cantor)           # 3.533 (King 2016 proxy)
hb.phi_ye(cantor)             # 34.82 (Ye 2015 proxy)

# Apply the canonical rules
from hea_bench.rules import guo_vec, king_phi, yang_omega, ye_phi, zhang_delta
zhang_delta.predict(cantor)          # 'single-phase'
yang_omega.predict(cantor)           # 'single-phase'
guo_vec.predict(cantor)              # 'FCC'
king_phi.predict(cantor)             # 'solid_solution'
ye_phi.predict(cantor)               # 'solid_solution'

These Cantor-alloy values are pinned in the test suite as the canonical sanity check. The rules are simple empirical surrogates — fast screens, not predictions; treat their output accordingly.

Quick start (oxides)

from hea_bench import oxides

# Rost 2015 "J14" entropy-stabilized rock salt
j14 = oxides.describe_rock_salt({"Mg": 1, "Co": 1, "Ni": 1, "Cu": 1, "Zn": 1})
j14["descriptors"]["s_config"]       # 13.382 J/(mol·K) = R·ln 5
j14["oxidation_states"]              # all 2+ by charge balance

# Jiang 2018 single-phase high-entropy perovskite
pvk = oxides.describe_perovskite({"Sr": 1}, {"Zr": 1, "Sn": 1, "Ti": 1, "Hf": 1, "Mn": 1})
pvk["descriptors"]["goldschmidt_t"]  # 0.979, inside the 0.92–1.04 window
pvk["verdicts"]["bartel"]            # 'perovskite' (τ = 3.72 < 4.18)

Each describe_* report carries the solved oxidation states, the Shannon radii actually used, every descriptor, the formability verdicts with their windows, and any warnings. See examples/02_oxides_walkthrough.py for the full tour, including the fluorite and pyrochlore screens and oxidation-state overrides.

Quick start (AI agents, MCP)

LLM agents hallucinate descriptor values; this server grounds them. hea_bench.mcp_server exposes the calculator over the Model Context Protocol as seven deterministic tools (parse_composition, batch alloy_descriptors and alloy_rules, omega_sensitivity, oxide_report, element_coverage, about). Every response carries units, the citation key of each parametrization, and the library version, so an agent's reasoning trace contains auditable receipts rather than bare floats.

pip install "hea-bench[mcp]"

Register it with any MCP client (Claude Desktop, Cursor, ...), for example in claude_desktop_config.json:

{ "mcpServers": { "hea-bench": { "command": "hea-bench-mcp" } } }

The omega_sensitivity tool is worth singling out: it reports the per-pair Miedema contributions and how far Ω moves when the dominant element's pair enthalpies are shifted within the spread of published compilations, so an agent can ask not just for a number but for how much to trust it.

Quick start (browser, no install)

A self-contained HTML calculator computes every descriptor, applies all six rules, runs the Miedema decompositions, and covers the oxide mode, entirely client-side. Two equivalent paths:

• Open the hosted site: https://dfieser.github.io/hea-bench/. The page is the calculator.
• Or clone the repo and open web/index.html — no install, no terminal, no server.

The calculator ships its own documentation: a Theory view deriving every alloy and oxide formula with citations, a grouped, filterable Equations reference, and a grouped References bibliography. Deep links open a view directly (index.html#theory, #equations, #refs). The parity-critical math lives in web/hea-calculator-core.js and is regression-checked against Python by the two parity test suites.

A note on Ω near ΔHmix ≈ 0

Ω = Tm·ΔSmix / |ΔHmix| diverges as ΔHmix → 0, so for near-ideal alloys (|ΔHmix| ≲ 1–2 kJ/mol) the Ω magnitude is extremely sensitive to the choice of Miedema pair table (sources disagree most on Mn). The phase verdict (Ω ≫ 1.1) stays robust even when the number does not — read Ω qualitatively in that regime.

Project layout

hea-bench/
├── src/hea_bench/
│   ├── descriptors/     ΔS_mix, δ, VEC, T_m, ΔH_mix, Ω, S_E, φ + data tables
│   ├── rules/           the six empirical phase-prediction rules
│   ├── oxides/          HEO module: families, oxidation-state solver,
│   │                    Shannon radii (94 elements, vendored from pymatgen)
│   ├── composition.py   formula parser, normalizer
│   ├── constants.py     R = 8.314
│   └── cli.py           command-line entry point
├── tests/               unit tests + BOTH Python↔JS parity suites
├── web/                 landing page + self-contained calculator (+ MathJax)
├── src-tauri/           native desktop wrapper (Rust/Tauri)
├── examples/            Cantor-alloy and oxides walkthroughs (.py + .ipynb)
└── pyproject.toml

Development

git clone https://github.com/dfieser/hea-bench
cd hea-bench
pip install -e ".[dev]"
python -m pytest tests/ -q          # includes the Python↔JS parity test (needs Node)

The HTML calculator (web/index.html over web/hea-calculator-core.js) is an independent JavaScript implementation of the same descriptors and rules. When you modify the Python descriptor code, update the JS core to match and re-run tests/test_web_parity.py and tests/test_web_oxides_parity.py so the surfaces don't drift. The element data tables inside the JS core are generated from the Python library by tests/data/_sync_js_tables.py and tests/data/_sync_js_oxide_tables.py — regenerate, never hand-edit.

License

MIT. The vendored matminer Miedema data files remain under their upstream BSD-3-Clause license, preserved at descriptors/data/LICENSE.matminer.txt.

Contributing and support

Contributions and bug reports are welcome. See CONTRIBUTING.md for development setup and the testing convention. To report a bug or ask a question, open a GitHub issue; for direct contact, email the maintainer at davjfies@gmail.com. Participation is governed by the Code of Conduct.

Citation

Citation metadata in CITATION.cff. When citing hea-bench, please also cite the primary sources for the parametrizations it implements: de Boer et al. 1988 for the Miedema model, the rule papers (Yeh 2004, Zhang 2008, Guo–Liu 2011, Yang–Zhang 2012, King 2016, Ye 2015), the oxide primaries (Shannon 1976, Goldschmidt 1926, Bartel 2019, Spiridigliozzi 2021, Subramanian 1983), matminer for the vendored pair table, and pymatgen for the Shannon-radius digitization. The full grouped bibliography is in the calculator's References view.

hea-bench is archived on Zenodo. The concept DOI 10.5281/zenodo.20346287 always resolves to the latest version.

Disclaimer

Descriptor values and rule predictions reported by hea-bench are empirical estimates for research and informational purposes only. The rules and descriptors are semi-empirical surrogates with known limitations. No warranty is made as to accuracy, completeness, fitness for any particular purpose, or suitability for material qualification. Do not use these outputs as the sole basis for engineering design or material qualification without independent verification by validated thermodynamic methods (e.g. CALPHAD or DFT).

Software is provided "as is" under the MIT License. Vendored Miedema elemental parameters from matminer remain under their upstream BSD-3-Clause license; see src/hea_bench/descriptors/data/LICENSE.matminer.txt.