Until now, "known" in Ouro's Crystal DB meant known to a DFT database. Now the novelty check also tells you whether a structure has been observed experimentally, and against which records.
COD is the largest open collection of experimentally determined crystal structures. All of it is now a public dataset on Ouro:
534,739 entries. Every released entry, with its formula, cell, space group, temperature, R factor and the paper it came from.
76,065 CIFs. We keep the CIF for every inorganic entry, as COD publishes it. Organic and metal-organic entries keep their metadata and link to COD.
CC0. Use it however you like, and please credit each structure's authors.
Most of COD's inorganic structures were published before 2000; organic structures took over after that. The dataset's Views tab also breaks the inorganic ones down by crystal system, number of elements, and most common elements.
Materials Project records whether each material has been observed, and which ICSD entries it was matched to. Our MP records now carry both:
48,892 of our 152,620 MP materials are flagged experimental.
51,225 carry ICSD collection codes.
Why not ICSD itself? Its license doesn't allow redistribution, so Ouro stores only the ICSD codes Materials Project links to, never ICSD data. COD is the open alternative.
Novelty now matches against COD alongside Materials Project, Alexandria and GNoME. Each match says whether it was observed experimentally, and the response has an experimentally_known flag. Here it is on COD's rock-salt NaCl:
NaCl (Fm-3m) matches mp-22862 (Materials Project) and 9 other published structures. It was observed experimentally (ICSD 18189, 28948, 41411).
Materialize takes COD ids too: "COD 1000041", the bare number, or a COD link. The CIF lands on Ouro under CC0, with the structure's own paper as its citation.
Two pulled in that way: NaCl from 1965, and α-quartz from 1935.
COD has no energies, so it's prior art for novelty, not part of the hull.
Matching uses the CIF as written. Partial occupancies and missing hydrogen positions match less often, and COD's formula field can differ from what its coordinates describe. reduced_formula and num_atoms in the dataset describe the coordinates.
"New" still means new to these databases, not to the literature.
The code is open: crystal-db has the COD build script (scripts/cod.py) and the matching code.
Please cite COD when you use it: Gražulis et al. 2009.
Every released entry of the Crystallography Open Database (COD): experimentally determined crystal structures of minerals, inorganic, metal-organic and organic compounds, one row per COD entry. Metadata for every entry: formula, cell, space group, temperature and pressure, R factor, method, and the paper it was published in (journal, year, DOI). The CIF itself for inorganic entries (no carbon-hydrogen compounds), as COD publishes it; the few largest lose the reflection data and SHELX files embedded in them. , and (sites in its primitive cell) describe that CIF as pymatgen reads it. is false for COD's few structures from calculations. and (retracted, warnings, errors) are COD's own. opens the entry on COD. Ouro's Crystal DB novelty check matches structures against these CIFs alongside Materials Project, Alexandria and GNoME. COD's data is in the public domain (CC0). Please acknowledge the original authors of each structure and cite COD: Gražulis et al., J. Appl. Cryst. 42, 726 (2009), doi:10.1107/S0021889809016690.
Match a CIF against every published structure with the same reduced formula in Materials Project, Alexandria, GNoME and the Crystallography Open Database (COD, experimental structures), using pymatgen's StructureMatcher on primitive cells with volume scaling (so DFT- and MLIP-relaxed versions of one crystal still match, as do supercells). Returns known (with the matching entries, closest first), new polymorph (the formula is published, this structure is not) or new composition (no published structure has the formula), plus any matching structures already made or submitted on Ouro. says whether a match was observed experimentally: a COD entry, or a Materials Project entry MP counts as experimental (with the ICSD collection codes MP matched it to). New means absent from these databases, not from the literature. Rejects overlapping-atom CIFs unless is set.
Look up a material by its Materials Project, Alexandria, GNoME or Crystallography Open Database id (e.g. mp-149, agm005272041, 0000a1b2c3, COD 1000041, or a link to its page) and save its crystal structure as a CIF file on Ouro, at the geometry the source published. Returns the formula and space group and, for the DFT databases, the source's PBE energy and the energy above the PBE hull of every structure in Ouro's crystal database. The file carries the record's license: CC BY 4.0 for Materials Project and Alexandria, CC BY-NC 4.0 (non-commercial use only) for GNoME and Materials Project's GNoME-derived records, CC0 for COD (whose file credits the structure's paper). The CIF credits its source.
Crystal structure of NaCl (Fm-3m) from the Crystallography Open Database (1000041), as its authors determined it. Published in Acta Crystallographica (1,1948-23,1967), 1965. 8 atoms per cell.
Crystal structure of SiO2 (P3121) from the Crystallography Open Database (1011097), as its authors determined it. Published in Zeitschrift fuer Kristallographie, Kristallgeometrie, Kristallphysik, Kristallchemie (-144,1977), 1935. 9 atoms per cell.
The Crystallography Open Database is now a public dataset on Ouro, and novelty checks now say whether a match was observed experimentally.