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Phase Diagram Generator

App slug: phase-diagram Category: Experimentalist Tools

The Phase Diagram Generator builds a convex-hull phase diagram for a selected chemical system using Materials Project entries and pymatgen. It can also evaluate user-submitted candidate phases by inserting them into the phase diagram and computing their energy above hull.

This app is designed for experimental materials scientists who want a quick stability map similar in spirit to OQMD-style phase-diagram tools, but using Materials Project data as the current backend source.

What The App Does

The app can:

query Materials Project entries for a chemical system such as Li-Fe-O
build a pymatgen PhaseDiagram
identify stable phases on the convex hull
list near-hull unstable phases
evaluate optional candidate formulas and energies
report decomposition products for unstable candidates
generate an interactive HTML phase-diagram plot when supported by pymatgen/Plotly
export CSV and JSON result files

Inputs

Chemical System

Enter a chemical system using chemsys=.

chemsys=Li-Fe-O

You can also enter the chemical system alone:

Li-Fe-O

The first version supports two, three, or four elements. Binary and ternary systems are the best suited for interactive plots.

Optional Candidate Phase

To evaluate one candidate:

chemsys=Li-Fe-O
formula=LiFeO2
formation_energy=-1.55

Candidate energies can be supplied as:

formation_energy=-1.55
energy_per_atom=-6.20
total_energy=-24.8

You can also add candidates using compact lines:

chemsys=Li-Fe-O
candidate=LiFeO2,-1.55
candidate=Li2FeO3,-1.42

For compact candidate=Formula,energy lines, the dropdown Default candidate energy type controls whether the number is interpreted as formation energy per atom, total energy per atom, or total energy.

Candidate CSV

Optional CSV columns:

Column	Meaning
`formula` or `composition`	Candidate formula
`formation_energy`	Formation energy per atom
`formation_energy_per_atom`	Formation energy per atom
`energy_per_atom`	Total energy per atom
`total_energy`	Total formula/cell energy
`energy`	Uses the selected default candidate energy type

Example:

formula,formation_energy
LiFeO2,-1.55
Li2FeO3,-1.42

Algorithm Summary

The backend workflow is:

1. Parse the chemical system. 2. Query Materials Project entries for the chemical system using mp-api. 3. Build a pymatgen PhaseDiagram from the MP entries. 4. Convert optional candidate phases into ComputedEntry objects. 5. Convert candidate formation energies to total energies using pymatgen elemental references. 6. Rebuild the phase diagram with MP entries plus user candidates. 7. Compute energy above hull for stable, near-hull, and candidate entries. 8. Compute decomposition products for unstable candidates. 9. Export tables, JSON, and an HTML phase-diagram plot.

Outputs

File	Description
`phase-diagram.html`	Interactive pymatgen/Plotly phase diagram when available
`phase-diagram-summary.csv`	Candidate, stable, and near-hull phase summary table
`phase-diagram-stable-phases.csv`	Stable hull phases
`phase-diagram-unstable-near-hull.csv`	Lowest-energy unstable MP phases
`phase-diagram-candidates.csv`	User candidate hull results
`phase-diagram-data.json`	Machine-readable result data

Important Notes

This app currently uses Materials Project, not OQMD, as the entry source.

The hull is only as reliable as the energy scale of the entries. If user candidate energies come from a different calculation setup, model, functional, or correction scheme, the absolute energy above hull can be misleading.

For publication-quality results, use internally consistent DFT energies and correction schemes.

Limitations

Binary and ternary systems are best for visual phase diagrams.
Quaternary systems are supported mainly through tables.
OQMD data is not yet integrated.
Experimental phase diagrams with temperature, pressure, entropy, and non-stoichiometry are not modeled.
Candidate energies must be compatible with Materials Project-style total energies if absolute hull values are needed.

Acknowledgements

This app uses pymatgen for phase-diagram construction and Materials Project data access through mp-api. Users should cite pymatgen and Materials Project when using the generated results in reports or publications.

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