Supported Source Datasets

ChemReporter currently supports the following source datasets:

• OMOL25 – Molecular systems, including bond-breaking, computed with hybrid DFT.

• OC20 – Periodic surface systems for adsorption and catalysis studies.

• OMAT24 – Periodic bulk inorganic materials.

• OMC25 – Periodic organic molecular crystals, relaxed with dispersion-corrected DFT.

• ODAC – Periodic MOF systems for direct air capture (DAC) applications.

Each dataset is handled by its own reader implementation, and these implementations are not interchangeable: they differ in how properties like subset are populated, which fields are read as-is from the source, and which are computed by ChemReporter. Read Crucial Implementation Details to understand these differences before processing and querying datasets.

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Computational Setup Details

The table below compares the computational details used across the supported source datasets. Column headers link to the primary reference paper for each dataset.

Setting	OMOL25	OC20	OMAT24	OMC25	ODAC
DFT Code	ORCA 6.0.0	VASP	VASP	VASP	Not reported
System Type	Molecular (non-periodic)	Periodic (surfaces)	Periodic (bulk materials)	Periodic (molecular crystals)	Periodic MOFs (DAC)
Basis Representation	Gaussian	Plane waves	Plane waves	Plane waves	Not reported
Basis Set	def2-TZVPD	—	—	—	—
Pseudopotentials / ECPs	def2 ECPs (elements 1–83 supported)	PAW	PAW	PAW	Not reported
Plane-Wave Cutoff	—	350 eV	520 eV (assuming MP default)	520 eV	Not reported
Exchange–Correlation	ωB97M-V	RPBE (GGA)	PBE (GGA)	PBE (GGA)	PBE (GGA)
Dispersion Treatment (Correction)	VV10 nonlocal correlation	D3	Hubbard +U	Grimme D3	D3 (PBE-D3)
Spin Treatment	UKS ; RKS also evaluated on subset	Spin-polarized when required	Spin-polarized	As set by relaxation workflow	Spin-polarized, initial magnetic moment +1 for all atoms
Integral / Acceleration	RI-J, COSX	—	—	—	Not reported
Grid / k-Points	DEFGRID3 (590 XC / 302 COSX angular points)	Monkhorst–Pack mesh	MP default k-point density	Via atomate2 RelaxSetGenerator	Not reported
Convergence Settings	Tight SCF; thresh=1e-12; tcut=1e-13	Force < 0.03 eV/Å or ≤200 ionic steps	Force < 0.03 eV/Å or ≤200 ionic steps	Max per-atom residual force < 0.001 eV/Å or ≤1,500 ionic steps; total energy tolerance 0.001 meV	Not reported

Crucial Implementation Details

Each source dataset is read by a dedicated implementation, selected via the database_format field of the process config (see Configuration). This maps to the following formats and readers:

database_format	Dataset	File format	Reader
aselmdb_omol	OMOL25	*.aselmdb	FairChem AseDBDataset
aselmdb_omat	OMAT24	*.aselmdb	FairChem AseDBDataset
aselmdb_oc	OC20	*.aselmdb	FairChem AseDBDataset
aselmdb_odac	ODAC23	*.aselmdb	FairChem AseDBDataset
aselmdb_omc	OMC25	*.aselmdb	FairChem AseDBDataset
xyz_oc	OC20 (extxyz)	*.extxyz.xz	ase.io + .pkl/.txt auxiliary files
xyz	generic extxyz	*.xyz	ase.io

Common Behavior Across Datasets

Beyond the per-dataset differences covered below, a few behaviors are shared by every implementation:

• database_name affects more than display. It is lowercased and _ is replaced by -, and it becomes part of every entry_key. For OC20 and OMAT24 it also carries the subset (see below), so a bare oc20 or omat24 raises SourceDatabaseReaderUsageError.

• DFT metadata (basis_set, functional, correction_term) is not read from the data itself; it comes verbatim from the source_database_metadata field of your process config (see Configuration) and is applied to every entry processed from that source database. It is optional, so leaving it out silently yields empty metadata columns.

• Charge and spin are either read from the source or enforced. OMOL25 and generic xyz store these values explicitly and they are read verbatim. All other datasets (OC20, OMAT24, OMC25, ODAC23) enforce net_charge = 0 (neutral) and spin_multiplicity = 1 (closed-shell) where applicable.

• subset drives graph-feature skipping. The subsets_skip_list list, set under graph_based_processing in your process config, is matched against subset to decide which entries skip graph-feature computation — so it has no effect for formats that never populate subset.

• Remote sources (s3://, …) are supported out of the box: files are downloaded into a temporary directory shard by shard and deleted again once each shard has been processed. See Custom I/O Plugins if you need to customize this behavior.

Dataset-Specific Details

OMOL25 (aselmdb_omol)

• Subsets come from the data. subset is read directly from atoms.info["data_id"], so splits such as spice, biomolecules, and elytes appear automatically — no naming convention is required on your side.

• net_charge (from charge), spin_multiplicity (from spin), num_atoms, and composition are all read straight from the source — this is the only dataset where all four fields are authoritative rather than inferred.

• Reactivity metadata is parsed from free text. For the rgd, reactivity, ani1, trans1x, and metal_complexes subsets, the free-text source field (and, for metal complexes, reference_source) is parsed into reaction_id, reaction_pathway_id, reaction_step_idx, is_reactant, and is_product. These columns stay null for every other subset. Unrecognized source strings yield nulls rather than raising, so partially-null reactivity columns are expected, not a bug.

• The metal_complexes subset renames itself to reactivity_metal_complexes, ground_state_metal_complexes, or failed_metal_complexes — filter on those names rather than on metal_complexes itself.

• The generic reactivity subset also renames its own subset, based on the first path segment of the free-text source field — known values include ani1xbb, pmechdb, and rmechdb — so filter on the resulting name rather than on reactivity itself.

• The HDF5 export automatically includes subset, charge, spin_multiplicity, num_atoms, mulliken_charges, and lowdin_charges.

OC20 (aselmdb_oc, xyz_oc)

• The subset isn’t in the data — it’s in the name. subset is derived as the last token of database_name after splitting on non-alphanumeric characters, so you must set database_name to something like oc20-s2ef or oc20-is2re. Only the last token is kept, so oc20-s2ef-all yields subset all.

• Needs supplementary files alongside the shards, for both aselmdb_oc and xyz_oc: a single oc20_data_mapping.pkl in the same directory, plus a per-shard auxiliary file (<shard>.txt or <shard>.txt.xz) providing sid, frame_number, and ref_energy. A sid missing from the pickle raises an error, as does a shard missing from the mapping.

• Charge and spin are enforced. net_charge is fixed at 0 (periodic slab supercells are neutral by construction), and spin_multiplicity is fixed at 1 (closed-shell).

• OC20 gets extra analysis This includes catalyst_adsorbate_smiles (OpenBabel is ran on the adsorbate alone), Note that adsorbate net charges are constrained within the range of -3 to +3, with the implementation prioritising neutral states whenever viable. catalyst_num_adsorbate_atoms, catalyst_num_bulk_atoms, catalyst_substrate_height (measured along the true surface normal, not the z-axis), catalyst_xyz_adsorbate_is_valid (whether the adsorbate sits above the slab and within its in-plane footprint, vdW-padded and minimum-image aware), and is_molecular_structure_valid (adsorbate plus nearby surface atoms). It also adds catalyst_bulk_id, catalyst_adsorbate_id, catalyst_bulk_symbols, catalyst_adsorbate_symbols, catalyst_miller_index, catalyst_reference_energy, catalyst_relaxation_frame_idx, and the decoded labels catalyst_class (intermetallics / metalloids / non-metals / halides) and catalyst_anomaly (no_anomaly / adsorbate_dissociation / adsorbate_desorption / surface_reconstruction / uninteracting_hydrogen).

• All catalyst_* columns exist only for OC20 — they are null for every other dataset.

• The HDF5 export automatically includes num_atoms.

OMAT24 (aselmdb_omat)

• The subset comes from the name, not the data. task_type is initially mapped to subset, but this is then overwritten with everything after the first delimiter of database_name, joined back together with - (so omat24-rattled-1000 becomes rattled-1000). Process one subset directory at a time and name it accordingly — a bare omat24 raises an error.

• composition is taken from composition_reduced, so — unlike every other dataset, where it reflects the full cell content — it is the reduced chemical formula.

• num_atoms is recomputed. net_charge is enforced at 0 (bulk cells are neutral by construction). spin_multiplicity is not set for OMAT24.

• The HDF5 export automatically includes subset, and stress.

OMC25 (aselmdb_omc)

• No subset at all. Nothing is mapped or derived, so subset always stays null — use database_name instead to distinguish between OMC25 runs.

• Everything else is derived from geometry: composition (full formula) and num_atoms. net_charge is enforced at 0 and spin_multiplicity at 1 (closed-shell)

• For OMC25, set source_database_metadata in your process config to basis_set: PAW-PW, functional: PBE, and correction_term: D3 (see the Computational Setup Details table above).

• The HDF5 export automatically includes stress (as a 3x3 matrix).

ODAC23 (aselmdb_odac)

• No subset

• num_atoms and composition are computed. net_charge is enforced at 0 and spin_multiplicity at 1 (closed-shell).

• No extra analysis columns and no extra HDF5 fields are automatically exported.

Generic extxyz (xyz)

• This is the escape hatch for your own data: subset is read from config_type, net_charge from total_charge, spin_multiplicity from spin, and num_atoms from num_atoms. energy and forces are rehydrated into a SinglePointCalculator when present in info/arrays.

• Nothing else is derived, so including those four keys in your extxyz headers is the cheapest way to get a fully populated Query Database.

• The HDF5 export automatically includes subset, charge, spin_multiplicity, and num_atoms.

What to check before querying

• Is subset populated for your dataset? For OMC25 and ODAC23 it isn’t — filter on database_name / split_name instead.

• For OC20 and OMAT24, did you encode the subset in database_name?

• Are net_charge / spin_multiplicity authoritative or enforced for the dataset you’re mixing in? OMOL25 and generic xyz read them from the source (ground truth). OC20, OMC25, and ODAC23 enforce 0 / 1 for all entries. OMAT24 enforces net_charge = 0 but leaves spin_multiplicity null. Mixing datasets means mixing ground truth with enforced constants.

• Dataset-specific columns (reaction_*, catalyst_*, stress, mulliken_charges, lowdin_charges) are null outside their source dataset — filtering on them silently drops every other dataset.