LeMaterial/LeMat-Bulk

Dataset Description

• —Homepage: https://www.lematerial.org/
• —Repository: https://github.com/lematerial/lematerial
• —Point of Contact: contact@lematerial.org

Motivation: check out the blog post https://huggingface.co/blog/lematerial to hear more about the motivation behind the creation of this dataset.

Changelog:

2025.04.17 (hash: NOT YET RELEASED):

• —We have changed the Yb default pseudopotential to Yb3 from VASP, this is the same that Materials Project uses. In the previous version we had kept it as Yb, and Materials Project had to Yb-containing materials. Alexandria and OQMD uses Yb. As a result no Yb-containing materials are crosscompatible=True in the latest iteration.
• —We have filtered out high-force materials (norm of forces > 0.1eV/A). The criteria is still quite large. This mostly affect Materials Project materials.
• —We have pulled the latest materials from Alexandria and Materials Project, as a result there are more materials in LeMat-Bulk and LeMat-Bulk-Unique
• —We have added energy_corrected field for the PBE subset using the Materials Project 2020 compatibility scheme across the entire dataset
• —We have added the international spacegroup number using Optimade's spacegroupit_number and computed using Moyopy
• —We have re-computed the hash using the BAWL fingerprint with the spacegroup processed by Moyopy and the entalpicfingerprint has been changed to bawlfingerprint. The fingerprint can be found in our newly released lematerial-hasher libary
• —We have added r2SCAN data from Materials Project
• —We used logic as defined in Materials Project's emmet package to select which MP task to include as the task representing the bulk material for MP materials.
• —We added certain validation tests, as defined in our newly released lematerial-fetcher library

Initial release, Dec 2024 (hash: 704b431aa574902f423b1c28f9b90c358d8cd1e1)

Download and use within Python

from datasets import load_dataset

dataset = load_dataset('LeMaterial/LeMat-Bulk', 'compatible_pbe')

# to use a specific database revision, based on the commit hash:
dataset = load_dataset('LeMaterial/LeMat-Bulk', 'compatible_pbe', revision='704b431aa574902f423b1c28f9b90c358d8cd1e1')

# convert to Pandas, if you prefer working with this type of object:
df = dataset['train'].to_pandas()

Data fields

Available subsets

To better support the diverse communities that may utilize this dataset, we are providing the following subsets of our database:

• —Compatible, PBE (default): This subset includes rows filtered to ensure cross-compatibility from a DFT perspective. For details on the filtering methodology, see the section below. Only PBE records are included. We designate this as the default subset to prevent accidental training of models on non-compatible data.
• —Compatible, PBESol: Similar to the Compatible, PBE subset, but includes only PBESol data.
• —Compatible, SCAN: Similar to the Compatible, PBE subset, but includes only SCAN data.
• —All: This includes all records formatted as described above. Disclaimer: Researchers must carefully evaluate the suitability of individual rows for their specific applications.

*Number of structures: only includes the output of resulting calculations from either a structure optimization for any available functional. For MP we do not consider all of their structures from the relaxation trajectory for instance, nor from tasks that are not structure optimization. For OQMD we only consider the output of structure relaxation as well, not accounting for any other calculations they performed.

Method for compatibility compliance

To ensure compatibility of rows from a DFT perspective, we implemented the following compatibility scheme:

• —Pseudopotentials: Calculations were verified to use consistent pseudopotentials. Notably, most pseudopotentials were aligned between MP and Alexandria, except for vanadium (where Alexandria used Vsv and MP used Vpv) and cesium (where Alexandria used a later version of the generic pseudopotential). For OQMD, this resulted in incompatibilities across records involving the following elements: Ca, Ti, V, Cr, Mn, Ru, Rh, Ce, Eu, Yb. We note that at the time of this release Materials Project deprecated all Yb containing materials due to the use of a pseudopotential that led to different than expected results. Thus no Yb containing materials from MP are in our database.
• —Hubbard U Parameters: To ensure uniformity in Hubbard U parameters, we excluded records containing oxygen (O) and any of the following elements: V, Cr, Mn, Fe, Ni, Cu, Th, U, Np, Pu, Mo, W. Similarly, records containing fluorine (F) and any of the following elements: Co, Cr, Fe, Mn, Mo, Ni, V, W were also excluded. This exclusion applied specifically to OQMD, which used different Hubbard U parameters compared to MP and Alexandria. However, records from OQMD containing O and Co were retained, as their Hubbard U parameter differed by only 0.02 eV.
• —Spin Polarization: OQMD only considered spin-polarized calculations for structures with d or f electrons. While non-spin-polarized calculations are not inherently incompatible (as they represent higher-energy magnetic phases compared to the ground state), we decided to exclude non-spin-polarized calculations for this release. This led to the removal of structures containing only the following elements: H, Li, Be, Na, Mg, K, Ca, Rb, Sr, Cs, Ba, Fr, Ra, B, C, N, O, F, Ne, He, Al, Si, P, S, Cl, Ar, Ga, Ge, As, Se, Br, Kr, In, Sn, Sb, Te, I, Xe, Tl, Pb, Bi, Po, At, Rn from OQMD.
• —Convergence Criteria: OQMD typically used a larger plane-wave cutoff but a less dense k-point grid. Despite these differences, we did not exclude records based on these parameters, assuming that OQMD, Alexandria, and MP operated within acceptable convergence zones for energy calculations. A similar approach was applied to other VASP parameters, though we welcome feedback on this assumption.
• —Convergence: Across all databases, we identified numerous records with potentially non-convergent calculations or high-energy configurations, often evidenced by significant atomistic forces. We chose not to exclude these records, as users can filter them easily using the “forces” tag if needed.
• —Energy Above the Hull: We opted not to filter materials with high energy above the hull, given the current scope of the dataset.

The “all” split does not contain any filtering based on this approach, so all records can be downloaded.

De-duplication method and our materials fingerprint

For our methods for finding duplicates across databases we creating a hasher function which works the following way:

• —We compute bonds using the EconNN algorithm already built in Pymatgen
• —We create a structure graph from this, encoding the species in the node
• —We hash this graph using Weisfeller-Lehman algorithm
• —We add symmetry and composition

Any structure which has a duplicate based on this method is dropped, only keeping the lowest energy structure. We benchmarked this to be robust to small gaussian noise on atomic positions, lattice vectors, and to respect detected symmetries in a structure. In searching for this method we tried to select one of the more sensitive bonding algorithms that would leave to the least amount of duplicates. We plan on releasing more information on this, as well as code to properly benchmark other fingerprint methods soon.

Check out these helpful spaces to understand the database

<figure class="table"> <table class="ck-table-resized"> <colgroup> <col style="width:50%;"> <col style="width:50%;"> </colgroup> <tbody> <tr> <td> <p style="text-align:center;"><figure class="image imageresized"><img src="https://huggingface.co/datasets/LeMaterial/admin/resolve/main/materialsexplorer.png"></figure></p> </td> <td> <p style="text-align:center;"><figure class="image imageresized"><img src="https://huggingface.co/datasets/LeMaterial/admin/resolve/main/TiNbSnLeMat110PD.png"></figure></p> </td> </tr> <tr> <td> <p style="text-align:center;"><a target="blank" rel="noopener noreferrer" href="https://huggingface.co/spaces/LeMaterial/materialsexplorer"><strong>Materials Explorer</strong></a></p> </td> <td> <p style="text-align:center;"><a target="blank" rel="noopener noreferrer" href="https://huggingface.co/spaces/LeMaterial/phasediagram"><strong>Phase Diagram</strong></a></p> </td> </tr> <tr> <td>Let's you browse entries in our database, view the crystal structure and its associated properties. Built using <a target="blank" rel="noopener noreferrer" href="https://github.com/materialsproject/dash-mp-components">Materials Project's dash components</a></td> <td>Lets you generate binary and ternary phase diagram using various correction scheme. Built using the Phase Diagram <a target="_blank" rel="noopener noreferrer" href="https://github.com/materialsproject/crystaltoolkit">Crystal Toolkit</a> component by the Materials Project<br><br><u>Disclaimer</u>: the MP2020 correction scheme has not yet been uniformed across datasets, when using this correction scheme please be cautious about interpreting data. We will fix this in upcoming release!</td> </tr> </tbody> </table> </figure>

Stay tuned for future updates

We plan to release very soon:

• —Band gap information on all materials, including direct and indirect band gaps.
• —Unification of energy corrections (currently a beta version of this is available for the purpose of the phase diagram application, but please see the disclaimer above).
• —Bader charges for all Materials Project materials where possible and the addition of charge data from Alexandria and OQMD
• —R2SCAN data from Materials Project

In the longer run we plan to release additional datasets including trajectories and surface, adsorbates, and molecules.

And more! Stay tuned.

Support

If you run into any issues regarding feel free to post your questions or comments on any of the following platforms:

• —**HF Discussions**
• —**Github Issues**

Citation Information

We are currently in the process of creating a pre-print to describe our methods, the materials fingerprint method and the dataset. For now however the following can be cited:

@misc {lematerial_2024,
	author = { {Martin Siron}, {Inel Djafar}, {Lucile Ritchie}, {Etienne Du-Fayet}, {Amandine Rossello}, {Ali Ramlaoui}, {Leandro von Werra}, {Thomas Wolf}, {Alexandre Duval} },
	title = { LeMat-Bulk Dataset },
	year = 2024,
	url = { https://huggingface.co/datasets/LeMaterial/LeMat-Bulk },
	doi = { 10.57967/hf/3762 },
	publisher = { Hugging Face }
}

CC-BY-4.0 (license used for Materials Project, Alexandria, OQMD) requires proper acknowledgement.

Thus, if you use materials data which include (”mp-”) in the immutable_id, please cite the Materials Project.

If you use materials data which include (”agm-”) in the immutable_id, please cite Alexandria, PBE or Alexandria PBESol, SCAN.

If you use materials data which include (”oqmd-”) in the immutable_id, please cite OQMD.

If you make use of Optimade in your research, please cite Optimade

Finally, if you make use of the Phase Diagram for visualization purposes, or the crystal viewer in the Materials Explorer, please acknowledge Crystal Toolkit.

License

This database is licensed by Creative Commons Attribution 4.0 License.

Disclaimer: it is made up of Alexandria, Materials Project and OQMD materials, which are all licensed by Creative Commons Attribution 4.0 License.