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FAQ

What formula notation is supported?

HEACalculator uses a flexible chemical formula parser that handles several common styles:

Style Example Notes
Equimolar (symbol-only) FeCoCrNi All elements treated as equal fractions
Explicit atom counts Fe25Co25Cr25Ni25 Counts are normalised internally
Nested brackets (FeCo)2CrNi Parentheses with multipliers
Mixed counts Fe10Co20Cr30Ni40 Any non-negative integer counts

Element symbols must start with an uppercase letter (Fe, not fe). Spaces inside the formula are not allowed.

What happens when I don't specify atom fractions?

If you provide a formula without numeric counts (e.g. FeCoCrNi), all elements are assumed to be equimolar. Internally the formula is treated as Fe1Co1Cr1Ni1 and the fractions are normalized to sum to 1.

How many elements are supported?

There is no hard limit on the number of components. However:

  • The mixing enthalpy and formation enthalpy databases cover a finite set of binary pairs. If a pair is missing, a MissingMixingEnthalpyError or MissingFormationEnthalpyError is raised.
  • Solid-solution criteria were derived for 5-component alloys and may be less reliable for 2- or 3-component systems.

Which prediction model should I trust?

No single model is universally reliable across all alloy families. As a rule of thumb:

  • Model 1 (Yang & Zhang) and Model 2 (Guo et al.) are the most widely cited and provide a good baseline.
  • Model 6 (Troparevsky et al.) is based on DFT formation enthalpies and tends to be more physically grounded.
  • Model 8 (King et al.) uses Gibbs free energy and is considered one of the more thermodynamically rigorous criteria.
  • Use multiple models together: if several agree, confidence is higher.

Does HEACalculator account for temperature effects?

Most parameters (density, VEC, delta, mixing enthalpy/entropy) are calculated at 0 K or use reference-temperature data. Exceptions:

  • omega is evaluated at the estimated melting temperature \(T_m\).
  • omega_at(T) can be called with an arbitrary temperature.
  • Model 6 evaluates formation enthalpies at \(0.55\,T_m\).
  • Model 7 defaults to an annealing temperature of \(0.60\,T_m\) (configurable).

Can I use HEACalculator as a Python library?

Yes. Install the package and import directly:

from HEACalculator import HEACalculator

hea = HEACalculator("AlCoCrFeNi")
print(hea.thermo.mixing_enthalpy)

See the Usage page for full examples.

How do I cite HEACalculator?

If you use HEACalculator in your research, please cite:

Doğuhan Sarıtürk. HEACalculator. (2019). doi:10.5281/zenodo.3590318

BibTeX 
@software{sariturk_2019_3590318,
  author    = {Sarıtürk, Doğuhan},
  title     = {HEACalculator},
  year      = 2019,
  publisher = {Zenodo},
  doi       = {10.5281/zenodo.3590318},
  url       = {https://doi.org/10.5281/zenodo.3590318},
}

You should also cite the original papers for any specific prediction models you rely on. See the Overview page for the full reference list.

What license is HEACalculator released under?

HEACalculator is distributed under the GNU General Public License v3.0 or later (GPL-3.0-or-later). See the LICENSE file for details.

How do I report a bug or request a feature?

Open an issue on GitHub: github.com/dogusariturk/HEACalculator/issues

How do I build the documentation locally?

uv sync --extra docs
uv run mkdocs serve

Then open http://127.0.0.1:8000 in your browser.