Skill v1.0.0
currentAutomated scan100/100version: "1.0.0" name: pymatgen description: Materials science toolkit. Crystal structures (CIF, POSCAR), phase diagrams, band structure, DOS, Materials Project integration, format conversion, for computational materials science. license: MIT license tags: [scientific-skills, pymatgen] metadata: skill-author: K-Dense Inc.
Pymatgen - Python Materials Genomics
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 Materials Project's database of computed materials. Supports 100+ file formats from various computational codes.
When to Use This Skill
This skill should be used 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 data (band gaps, DOS, band structures)
- Generating surfaces, slabs, or studying interfaces
- Accessing the Materials Project database programmatically
- Setting up high-throughput computational workflows
- Analyzing diffusion, magnetism, or mechanical properties
- Working with VASP, Gaussian, Quantum ESPRESSO, or other computational codes
Quick Start Guide
Installation
# Core pymatgenuv pip install pymatgen# With Materials Project API accessuv pip install pymatgen mp-api# Optional dependencies for extended functionalityuv pip install pymatgen[analysis] # Additional analysis toolsuv pip install pymatgen[vis] # Visualization tools
Basic Structure Operations
from pymatgen.core import Structure, Lattice# Read structure from file (automatic format detection)struct = Structure.from_file("POSCAR")# Create structure from scratchlattice = Lattice.cubic(3.84)struct = Structure(lattice, ["Si", "Si"], [[0,0,0], [0.25,0.25,0.25]])# Write to different formatstruct.to(filename="structure.cif")# Basic propertiesprint(f"Formula: {struct.composition.reduced_formula}")print(f"Space group: {struct.get_space_group_info()}")print(f"Density: {struct.density:.2f} g/cm³")
Materials Project Integration
# Set up API keyexport MP_API_KEY="your_api_key_here"
from mp_api.client import MPResterwith MPRester() as mpr:# Get structure by material IDstruct = mpr.get_structure_by_material_id("mp-149")# Search for materialsmaterials = mpr.materials.summary.search(formula="Fe2O3",energy_above_hull=(0, 0.05))
Core Capabilities
1. Structure Creation and Manipulation
Create structures using various methods and perform transformations.
From files:
# Automatic format detectionstruct = Structure.from_file("structure.cif")struct = Structure.from_file("POSCAR")mol = Molecule.from_file("molecule.xyz")
From scratch:
from pymatgen.core import Structure, Lattice# Using lattice parameterslattice = Lattice.from_parameters(a=3.84, b=3.84, c=3.84,alpha=120, beta=90, gamma=60)coords = [[0, 0, 0], [0.75, 0.5, 0.75]]struct = Structure(lattice, ["Si", "Si"], coords)# From space groupstruct = Structure.from_spacegroup("Fm-3m",Lattice.cubic(3.5),["Si"],[[0, 0, 0]])
Transformations:
from pymatgen.transformations.standard_transformations import (SupercellTransformation,SubstitutionTransformation,PrimitiveCellTransformation)# Create supercelltrans = SupercellTransformation([[2,0,0],[0,2,0],[0,0,2]])supercell = trans.apply_transformation(struct)# Substitute elementstrans = SubstitutionTransformation({"Fe": "Mn"})new_struct = trans.apply_transformation(struct)# Get primitive celltrans = PrimitiveCellTransformation()primitive = trans.apply_transformation(struct)
Reference: See references/core_classes.md for comprehensive documentation of Structure, Lattice, Molecule, and related classes.
2. File Format Conversion
Convert between 100+ file formats with automatic format detection.
Using convenience methods:
# Read any formatstruct = Structure.from_file("input_file")# Write to any formatstruct.to(filename="output.cif")struct.to(filename="POSCAR")struct.to(filename="output.xyz")
Using the conversion script:
# Single file conversionpython scripts/structure_converter.py POSCAR structure.cif# Batch conversionpython scripts/structure_converter.py *.cif --output-dir ./poscar_files --format poscar
Reference: See references/io_formats.md for detailed documentation of all supported formats and code integrations.
3. Structure Analysis and Symmetry
Analyze structures for symmetry, coordination, and other properties.
Symmetry analysis:
from pymatgen.symmetry.analyzer import SpacegroupAnalyzersga = SpacegroupAnalyzer(struct)# Get space group informationprint(f"Space group: {sga.get_space_group_symbol()}")print(f"Number: {sga.get_space_group_number()}")print(f"Crystal system: {sga.get_crystal_system()}")# Get conventional/primitive cellsconventional = sga.get_conventional_standard_structure()primitive = sga.get_primitive_standard_structure()
Coordination environment:
from pymatgen.analysis.local_env import CrystalNNcnn = CrystalNN()neighbors = cnn.get_nn_info(struct, n=0) # Neighbors of site 0print(f"Coordination number: {len(neighbors)}")for neighbor in neighbors:site = struct[neighbor['site_index']]print(f" {site.species_string} at {neighbor['weight']:.3f} Å")
Using the analysis script:
# Comprehensive analysispython scripts/structure_analyzer.py POSCAR --symmetry --neighbors# Export resultspython scripts/structure_analyzer.py structure.cif --symmetry --export json
Reference: See references/analysis_modules.md for detailed documentation of all analysis capabilities.
4. Phase Diagrams and Thermodynamics
Construct phase diagrams and analyze thermodynamic stability.
Phase diagram construction:
from mp_api.client import MPResterfrom pymatgen.analysis.phase_diagram import PhaseDiagram, PDPlotter# Get entries from Materials Projectwith MPRester() as mpr:entries = mpr.get_entries_in_chemsys("Li-Fe-O")# Build phase diagrampd = PhaseDiagram(entries)# Check stabilityfrom pymatgen.core import Compositioncomp = Composition("LiFeO2")# Find entry for compositionfor entry in entries:if entry.composition.reduced_formula == comp.reduced_formula:e_above_hull = pd.get_e_above_hull(entry)print(f"Energy above hull: {e_above_hull:.4f} eV/atom")if e_above_hull > 0.001:# Get decompositiondecomp = pd.get_decomposition(comp)print("Decomposes to:", decomp)# Plotplotter = PDPlotter(pd)plotter.show()
Using the phase diagram script:
# Generate phase diagrampython scripts/phase_diagram_generator.py Li-Fe-O --output li_fe_o.png# Analyze specific compositionpython scripts/phase_diagram_generator.py Li-Fe-O --analyze "LiFeO2" --show
Reference: See references/analysis_modules.md (Phase Diagrams section) and references/transformations_workflows.md (Workflow 2) for detailed examples.
5. Electronic Structure Analysis
Analyze band structures, density of states, and electronic properties.
Band structure:
from pymatgen.io.vasp import Vasprunfrom pymatgen.electronic_structure.plotter import BSPlotter# Read from VASP calculationvasprun = Vasprun("vasprun.xml")bs = vasprun.get_band_structure()# Analyzeband_gap = bs.get_band_gap()print(f"Band gap: {band_gap['energy']:.3f} eV")print(f"Direct: {band_gap['direct']}")print(f"Is metal: {bs.is_metal()}")# Plotplotter = BSPlotter(bs)plotter.save_plot("band_structure.png")
Density of states:
from pymatgen.electronic_structure.plotter import DosPlotterdos = vasprun.complete_dos# Get element-projected DOSelement_dos = dos.get_element_dos()for element, element_dos_obj in element_dos.items():print(f"{element}: {element_dos_obj.get_gap():.3f} eV")# Plotplotter = DosPlotter()plotter.add_dos("Total DOS", dos)plotter.show()
Reference: See references/analysis_modules.md (Electronic Structure section) and references/io_formats.md (VASP section).
6. Surface and Interface Analysis
Generate slabs, analyze surfaces, and study interfaces.
Slab generation:
from pymatgen.core.surface import SlabGenerator# Generate slabs for specific Miller indexslabgen = SlabGenerator(struct,miller_index=(1, 1, 1),min_slab_size=10.0, # Åmin_vacuum_size=10.0, # Åcenter_slab=True)slabs = slabgen.get_slabs()# Write slabsfor i, slab in enumerate(slabs):slab.to(filename=f"slab_{i}.cif")
Wulff shape construction:
from pymatgen.analysis.wulff import WulffShape# Define surface energiessurface_energies = {(1, 0, 0): 1.0,(1, 1, 0): 1.1,(1, 1, 1): 0.9,}wulff = WulffShape(struct.lattice, surface_energies)print(f"Surface area: {wulff.surface_area:.2f} Ų")print(f"Volume: {wulff.volume:.2f} ų")wulff.show()
Adsorption site finding:
from pymatgen.analysis.adsorption import AdsorbateSiteFinderfrom pymatgen.core import Moleculeasf = AdsorbateSiteFinder(slab)# Find sitesads_sites = asf.find_adsorption_sites()print(f"On-top sites: {len(ads_sites['ontop'])}")print(f"Bridge sites: {len(ads_sites['bridge'])}")print(f"Hollow sites: {len(ads_sites['hollow'])}")# Add adsorbateadsorbate = Molecule("O", [[0, 0, 0]])ads_struct = asf.add_adsorbate(adsorbate, ads_sites["ontop"][0])
Reference: See references/analysis_modules.md (Surface and Interface section) and references/transformations_workflows.md (Workflows 3 and 9).
7. Materials Project Database Access
Programmatically access the Materials Project database.
Setup:
- Get API key from https://next-gen.materialsproject.org/
- Set environment variable:
export MP_API_KEY="your_key_here"
Search and retrieve:
from mp_api.client import MPResterwith MPRester() as mpr:# Search by formulamaterials = mpr.materials.summary.search(formula="Fe2O3")# Search by chemical systemmaterials = mpr.materials.summary.search(chemsys="Li-Fe-O")# Filter by propertiesmaterials = mpr.materials.summary.search(chemsys="Li-Fe-O",energy_above_hull=(0, 0.05), # Stable/metastableband_gap=(1.0, 3.0) # Semiconducting)# Get structurestruct = mpr.get_structure_by_material_id("mp-149")# Get band structurebs = mpr.get_bandstructure_by_material_id("mp-149")# Get entries for phase diagramentries = mpr.get_entries_in_chemsys("Li-Fe-O")
Reference: See references/materials_project_api.md for comprehensive API documentation and examples.
8. Computational Workflow Setup
Set up calculations for various electronic structure codes.
VASP input generation:
from pymatgen.io.vasp.sets import MPRelaxSet, MPStaticSet, MPNonSCFSet# Relaxationrelax = MPRelaxSet(struct)relax.write_input("./relax_calc")# Static calculationstatic = MPStaticSet(struct)static.write_input("./static_calc")# Band structure (non-self-consistent)nscf = MPNonSCFSet(struct, mode="line")nscf.write_input("./bandstructure_calc")# Custom parameterscustom = MPRelaxSet(struct, user_incar_settings={"ENCUT": 600})custom.write_input("./custom_calc")
Other codes:
# Gaussianfrom pymatgen.io.gaussian import GaussianInputgin = GaussianInput(mol,functional="B3LYP",basis_set="6-31G(d)",route_parameters={"Opt": None})gin.write_file("input.gjf")# Quantum ESPRESSOfrom pymatgen.io.pwscf import PWInputpwin = PWInput(struct, control={"calculation": "scf"})pwin.write_file("pw.in")
Reference: See references/io_formats.md (Electronic Structure Code I/O section) and references/transformations_workflows.md for workflow examples.
9. Advanced Analysis
Diffraction patterns:
from pymatgen.analysis.diffraction.xrd import XRDCalculatorxrd = XRDCalculator()pattern = xrd.get_pattern(struct)# Get peaksfor peak in pattern.hkls:print(f"2θ = {peak['2theta']:.2f}°, hkl = {peak['hkl']}")pattern.plot()
Elastic properties:
from pymatgen.analysis.elasticity import ElasticTensor# From elastic tensor matrixelastic_tensor = ElasticTensor.from_voigt(matrix)print(f"Bulk modulus: {elastic_tensor.k_voigt:.1f} GPa")print(f"Shear modulus: {elastic_tensor.g_voigt:.1f} GPa")print(f"Young's modulus: {elastic_tensor.y_mod:.1f} GPa")
Magnetic ordering:
from pymatgen.transformations.advanced_transformations import MagOrderingTransformation# Enumerate magnetic orderingstrans = MagOrderingTransformation({"Fe": 5.0})mag_structs = trans.apply_transformation(struct, return_ranked_list=True)# Get lowest energy magnetic structurelowest_energy_struct = mag_structs[0]['structure']
Reference: See references/analysis_modules.md for comprehensive analysis module documentation.
Bundled Resources
Scripts (scripts/)
Executable Python scripts for common tasks:
- `structure_converter.py`: Convert between structure file formats
- Supports batch conversion and automatic format detection
- Usage:
python scripts/structure_converter.py POSCAR structure.cif
- `structure_analyzer.py`: Comprehensive structure analysis
- Symmetry, coordination, lattice parameters, distance matrix
- Usage:
python scripts/structure_analyzer.py structure.cif --symmetry --neighbors
- `phase_diagram_generator.py`: Generate phase diagrams from Materials Project
- Stability analysis and thermodynamic properties
- Usage:
python scripts/phase_diagram_generator.py Li-Fe-O --analyze "LiFeO2"
All scripts include detailed help: python scripts/script_name.py --help
References (references/)
Comprehensive documentation loaded into context as needed:
- `core_classes.md`: Element, Structure, Lattice, Molecule, Composition classes
- `io_formats.md`: File format support and code integration (VASP, Gaussian, etc.)
- `analysis_modules.md`: Phase diagrams, surfaces, electronic structure, symmetry
- `materials_project_api.md`: Complete Materials Project API guide
- `transformations_workflows.md`: Transformations framework and common workflows
Load references when detailed information is needed about specific modules or workflows.
Common Workflows
High-Throughput Structure Generation
from pymatgen.transformations.standard_transformations import SubstitutionTransformationfrom pymatgen.io.vasp.sets import MPRelaxSet# Generate doped structuresbase_struct = Structure.from_file("POSCAR")dopants = ["Mn", "Co", "Ni", "Cu"]for dopant in dopants:trans = SubstitutionTransformation({"Fe": dopant})doped_struct = trans.apply_transformation(base_struct)# Generate VASP inputsvasp_input = MPRelaxSet(doped_struct)vasp_input.write_input(f"./calcs/Fe_{dopant}")
Band Structure Calculation Workflow
# 1. Relaxationrelax = MPRelaxSet(struct)relax.write_input("./1_relax")# 2. Static (after relaxation)relaxed = Structure.from_file("1_relax/CONTCAR")static = MPStaticSet(relaxed)static.write_input("./2_static")# 3. Band structure (non-self-consistent)nscf = MPNonSCFSet(relaxed, mode="line")nscf.write_input("./3_bandstructure")# 4. Analysisfrom pymatgen.io.vasp import Vasprunvasprun = Vasprun("3_bandstructure/vasprun.xml")bs = vasprun.get_band_structure()bs.get_band_gap()
Surface Energy Calculation
# 1. Get bulk energybulk_vasprun = Vasprun("bulk/vasprun.xml")bulk_E_per_atom = bulk_vasprun.final_energy / len(bulk)# 2. Generate and calculate slabsslabgen = SlabGenerator(bulk, (1,1,1), 10, 15)slab = slabgen.get_slabs()[0]MPRelaxSet(slab).write_input("./slab_calc")# 3. Calculate surface energy (after calculation)slab_vasprun = Vasprun("slab_calc/vasprun.xml")E_surf = (slab_vasprun.final_energy - len(slab) * bulk_E_per_atom) / (2 * slab.surface_area)E_surf *= 16.021766 # Convert eV/Ų to J/m²
More workflows: See references/transformations_workflows.md for 10 detailed workflow examples.
Best Practices
Structure Handling
- Use automatic format detection:
Structure.from_file()handles most formats - Prefer immutable structures: Use
IStructurewhen structure shouldn't change - Check symmetry: Use
SpacegroupAnalyzerto reduce to primitive cell - Validate structures: Check for overlapping atoms or unreasonable bond lengths
File I/O
- Use convenience methods:
from_file()andto()are preferred - Specify formats explicitly: When automatic detection fails
- Handle exceptions: Wrap file I/O in try-except blocks
- Use serialization:
as_dict()/from_dict()for version-safe storage
Materials Project API
- Use context manager: Always use
with MPRester() as mpr: - Batch queries: Request multiple items at once
- Cache results: Save frequently used data locally
- Filter effectively: Use property filters to reduce data transfer
Computational Workflows
- Use input sets: Prefer
MPRelaxSet,MPStaticSetover manual INCAR - Check convergence: Always verify calculations converged
- Track transformations: Use
TransformedStructurefor provenance - Organize calculations: Use clear directory structures
Performance
- Reduce symmetry: Use primitive cells when possible
- Limit neighbor searches: Specify reasonable cutoff radii
- Use appropriate methods: Different analysis tools have different speed/accuracy tradeoffs
- Parallelize when possible: Many operations can be parallelized
Units and Conventions
Pymatgen uses atomic units throughout:
- Lengths: Angstroms (Å)
- Energies: Electronvolts (eV)
- Angles: Degrees (°)
- Magnetic moments: Bohr magnetons (μB)
- Time: Femtoseconds (fs)
Convert units using pymatgen.core.units when needed.
Integration with Other Tools
Pymatgen integrates seamlessly with:
- ASE (Atomic Simulation Environment)
- Phonopy (phonon calculations)
- BoltzTraP (transport properties)
- Atomate/Fireworks (workflow management)
- AiiDA (provenance tracking)
- Zeo++ (pore analysis)
- OpenBabel (molecule conversion)
Troubleshooting
Import errors: Install missing dependencies
uv pip install pymatgen[analysis,vis]
API key not found: Set MP_API_KEY environment variable
export MP_API_KEY="your_key_here"
Structure read failures: Check file format and syntax
# Try explicit format specificationstruct = Structure.from_file("file.txt", fmt="cif")
Symmetry analysis fails: Structure may have numerical precision issues
# Increase tolerancefrom pymatgen.symmetry.analyzer import SpacegroupAnalyzersga = SpacegroupAnalyzer(struct, symprec=0.1)
Additional Resources
- Documentation: https://pymatgen.org/
- Materials Project: https://materialsproject.org/
- GitHub: https://github.com/materialsproject/pymatgen
- Forum: https://matsci.org/
- Example notebooks: https://matgenb.materialsvirtuallab.org/
Version Notes
This skill is designed for pymatgen 2024.x and later. For the Materials Project API, use the mp-api package (separate from legacy pymatgen.ext.matproj).
Requirements:
- Python 3.10 or higher
- pymatgen >= 2023.x
- mp-api (for Materials Project access)