The dataset viewer is not available for this subset.
Exception: SplitsNotFoundError
Message: The split names could not be parsed from the dataset config.
Traceback: Traceback (most recent call last):
File "/usr/local/lib/python3.14/site-packages/datasets/inspect.py", line 286, in get_dataset_config_info
for split_generator in builder._split_generators(
~~~~~~~~~~~~~~~~~~~~~~~~~^
StreamingDownloadManager(base_path=builder.base_path, download_config=download_config)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "/usr/local/lib/python3.14/site-packages/datasets/packaged_modules/webdataset/webdataset.py", line 80, in _split_generators
raise ValueError(
...<2 lines>...
)
ValueError: The TAR archives of the dataset should be in WebDataset format, but the files in the archive don't share the same prefix or the same types.
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "/src/services/worker/src/worker/job_runners/config/split_names.py", line 68, in compute_split_names_from_streaming_response
for split in get_dataset_split_names(
~~~~~~~~~~~~~~~~~~~~~~~^
path=dataset,
^^^^^^^^^^^^^
config_name=config,
^^^^^^^^^^^^^^^^^^^
token=hf_token,
^^^^^^^^^^^^^^^
)
^
File "/usr/local/lib/python3.14/site-packages/datasets/inspect.py", line 340, in get_dataset_split_names
info = get_dataset_config_info(
path,
...<6 lines>...
**config_kwargs,
)
File "/usr/local/lib/python3.14/site-packages/datasets/inspect.py", line 291, in get_dataset_config_info
raise SplitsNotFoundError("The split names could not be parsed from the dataset config.") from err
datasets.inspect.SplitsNotFoundError: The split names could not be parsed from the dataset config.Need help to make the dataset viewer work? Make sure to review how to configure the dataset viewer, and open a discussion for direct support.
Dataset
Materials project (2019 dump)
This dataset contains 133420 materials with formation energy per atom.
Processed from mp.2019.04.01.json
Download
Download link: materials-project.tar.gz
MD5 checksum c132f3781f32cd17f3a92aa6501b9531
Content
Bundled in materials-project.tar.gz.
Index (index.json)
list of dict:
index(int) => index of the structure in data file.id(str) => id of Materials Project.formula(str) => formula.natoms(int) => number of atoms.energy_pa(float) => formation energy per atom.
Data (data.hdf5)
fields:
structures=> a group containing structure information.structures/cell(float32) => lattice of the material.structures/natoms(int32) => number of atoms.structures/energy_pa(float32) => formation energy per atom.structures/atoms_ptr(int64) => position of the first atom of the structures in theatomsgroup.atoms=> a group containing information about atoms.atoms/positions(float32) => the positions of the atoms.atoms/atomic_number(uint8) => the atomic number of the atoms.
2026 release (all.hdf5)
all.hdf5 is a newer, separate export of the Materials Project, preprocessed with
pycrystalgen. It does not replace materials-project.tar.gz above and uses a different layout.
It contains 271,325 structures (6,967,262 atoms, 1 to 444 atoms per structure): every
material of the summary collection of database version 2026.09.28, except the 8,834
materials flagged as deprecated. Nothing else is filtered.
Labels
| Field | Source column | Meaning |
|---|---|---|
total_energy |
energy_per_atom × nsites |
total energy of the cell in eV, with the corrections of the Materials Project |
formation_energy_per_atom |
formation_energy_per_atom |
formation energy in eV/atom |
energy_above_hull |
energy_above_hull |
energy above the convex hull in eV/atom |
band_gap |
band_gap |
band gap in eV |
Four materials have no labels in the source and are kept with NaN. Material ids are not stored: structures are in the order of the source collection, deprecated materials removed.
Format
Flat concatenated arrays:
| Dataset | Shape | Type | Content |
|---|---|---|---|
lattice |
(n_struct, 3, 3) | float32 | lattice vectors as rows, in angstrom |
num_atoms |
(n_struct,) | int64 | number of atoms of each structure |
ptr |
(n_struct,) | int64 | index of the first atom of each structure in x and z |
x |
(n_atoms, 3) | float32 | fractional coordinates in [0, 1) |
z |
(n_atoms,) | int64 | atomic numbers |
total_energy, formation_energy_per_atom, energy_above_hull, band_gap |
(n_struct,) | float32 | labels, NaN when unknown |
The lattice is rebuilt from cell lengths and angles, so it is in the standard orientation
(first vector along x). The batch array is an artefact of the writer and is not used when
reading.
Usage
from pycrystalgen.data import HDF5Dataset
dataset = HDF5Dataset.from_hub("materials-toolkits/materials-project", "all.hdf5")
structures = dataset[:32] # batched Structures
Source, processing and licence
- Source: the public open data bucket of the Materials Project,
materialsproject-build/collections/summary/version=2026-09-28/. - Built with pycrystalgen,
scripts/build_materials_project.py: collection to CIF, then CIF to HDF5. - Every structure was checked against the source: number of atoms, elements, fractional coordinates, lattice and the four labels.
Licence of all.hdf5: the license: mit of this repository describes the 2019 files, not
this one. In the source, each material carries its own licence label: 154,377 of the
structures kept here are labelled BY-C and 116,948 are labelled BY-NC (non-commercial).
This file does not record which structure has which label, so treat the whole file as
non-commercial unless you check against the source, and refer to the Materials Project for
the terms of use.
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