Overview
Pymatgen is a comprehensive Python library for materials analysis that powers the Materials Project. Create, analyze, and manipulate crystal structures and molecules; compute phase diagrams and thermodynamic properties; analyze electronic structure (band structures, DOS); generate surfaces and interfaces; and access the Materials Project database. Supports 100+ file formats from various computational codes.
When to Use This Skill
Use when:
- Working with crystal structures or molecular systems in materials science
- Converting between structure file formats (CIF, POSCAR, XYZ, etc.)
- Analyzing symmetry, space groups, or coordination environments
- Computing phase diagrams or assessing thermodynamic stability
- Analyzing electronic structure (band gaps, DOS, band structures)
- Generating surfaces/slabs or studying interfaces
- Accessing the Materials Project database programmatically
- Setting up high-throughput computational workflows
- Working with VASP, Gaussian, Quantum ESPRESSO, or other codes
Does NOT Trigger
| Scenario | Use Instead |
|---|---|
| Small organic molecules — SMILES, fingerprints, descriptors, substructure search | alterlab-rdkit |
| Running DFT / conformer searches / pKa in a managed cloud quantum-chemistry service | alterlab-rowan |
| Classical molecular dynamics of proteins or ligands (OpenMM, trajectories) | alterlab-molecular-dynamics |
| Variational quantum circuits for molecular ground states (VQE) | alterlab-pennylane |
Quick Start
uv pip install pymatgen # core (Python >= 3.11)
uv pip install pymatgen mp-api # + Materials Project API access
uv pip install "pymatgen[optional]" # extra analysis deps (phonopy, seekpath, ase, ...)
uv pip install "pymatgen[vis]" # VTK structure visualization
from pymatgen.core import Structure, Lattice
struct = Structure.from_file("POSCAR") # auto format detection
struct.to(filename="structure.cif") # write any format
print(struct.composition.reduced_formula)
print(struct.get_space_group_info())
print(f"{struct.density:.2f} g/cm³")
export MP_API_KEY="your_api_key_here" # for Materials Project access
Core Capabilities (routing)
Each capability has a copy-paste code block in references/core_examples.md and deeper
module docs in the references listed below.
- Structure creation & manipulation — from files, from scratch (lattice params or
space group), transformations (supercell, substitution, primitive). →
core_classes.md - File-format conversion —
from_file()/to()plusscripts/structure_converter.pyfor single/batch. →io_formats.md - Structure analysis & symmetry —
SpacegroupAnalyzer,CrystalNN, plusscripts/structure_analyzer.py. →analysis_modules.md - Phase diagrams & thermodynamics —
PhaseDiagram, energy-above-hull, decomposition, plusscripts/phase_diagram_generator.py. →analysis_modules.md,transformations_workflows.md - Electronic structure — band structures and DOS from
Vasprun, band gaps, metallicity. →analysis_modules.md,io_formats.md - Surfaces & interfaces —
SlabGenerator,WulffShape,AdsorbateSiteFinder. →analysis_modules.md,transformations_workflows.md - Materials Project access —
MPRestersearch and retrieval with property filters. →materials_project_api.md - Computational workflow setup — VASP input sets (
MPRelaxSet,MPStaticSet,MPNonSCFSet), Gaussian, Quantum ESPRESSO. →io_formats.md,transformations_workflows.md - Advanced analysis — XRD patterns, elastic tensors, magnetic ordering.
→
analysis_modules.md
Multi-step worked examples (high-throughput generation, band-structure pipeline, surface
energy): references/common_workflows_code.md.
Bundled Resources
Scripts (scripts/)
structure_converter.py: convert between structure file formats (batch + auto detection). Usage:python scripts/structure_converter.py POSCAR structure.cifstructure_analyzer.py: symmetry, coordination, lattice parameters, distance matrix. Usage:python scripts/structure_analyzer.py structure.cif --symmetry --neighborsphase_diagram_generator.py: phase diagrams from Materials Project, stability analysis. Usage:python scripts/phase_diagram_generator.py Li-Fe-O --analyze "LiFeO2"
All scripts include detailed help, e.g. python scripts/structure_converter.py --help
References (references/)
core_examples.md: copy-paste code for all nine core capabilitiescommon_workflows_code.md: multi-step worked workflow codecore_classes.md: Element, Structure, Lattice, Molecule, Composition classesio_formats.md: file-format support and code integration (VASP, Gaussian, etc.)analysis_modules.md: phase diagrams, surfaces, electronic structure, symmetrymaterials_project_api.md: complete Materials Project API guidetransformations_workflows.md: transformations framework and 10 common workflows
Best Practices
Structures: use auto format detection; prefer IStructure when immutable; reduce to
primitive cell with SpacegroupAnalyzer; validate for overlapping atoms / bad bond
lengths. File I/O: prefer from_file()/to(); specify format when detection fails;
use as_dict()/from_dict() for version-safe storage. MP API: always use the context
manager; batch queries; cache results; filter by property. Workflows: prefer input
sets over manual INCAR; verify convergence; track transformations for provenance.
Performance: use primitive cells; bound neighbor-search cutoffs; parallelize where
possible.
Units and Conventions
Lengths in Å, energies in eV, angles in degrees, magnetic moments in μB, time in fs.
Convert with pymatgen.core.units.
Integration
Integrates with ASE, Phonopy, BoltzTraP, Atomate/Fireworks, AiiDA, Zeo++, and OpenBabel.
Troubleshooting
- Import errors:
uv pip install "pymatgen[optional,vis]"(there is no[analysis]extra) - API key not found:
export MP_API_KEY="your_key_here" - Structure read failures: try explicit format, e.g.
Structure.from_file("file.txt", fmt="cif") - Symmetry analysis fails: increase tolerance, e.g.
SpacegroupAnalyzer(struct, symprec=0.1)
Additional Resources
Docs: https://pymatgen.org/ · Materials Project: https://materialsproject.org/ · GitHub: https://github.com/materialsproject/pymatgen · Forum: https://matsci.org/ · Example notebooks: https://github.com/materialsvirtuallab/matgenb
Version Notes
Designed for pymatgen 2024.x and later (current 2026.9.x as of 2026-09; calendar
versioning). Since 2026 the pymatgen distribution is a thin package on top of
pymatgen-core; imports (pymatgen.core, pymatgen.io.vasp, …) are unchanged. For the
Materials Project API use the mp-api package (current 0.46.x; from mp_api.client import MPRester) rather than the legacy pymatgen.ext.matproj client. Requirements: Python ≥ 3.11,
pymatgen ≥ 2024.x, mp-api for Materials Project access.
Part of the AlterLab Academic Skills suite.