ICSD: Inorganic Crystal Structure Database Guide

The Inorganic Crystal Structure Database (ICSD) is the definitive international repository for fully evaluated and identified inorganic crystal structures. Produced by FIZ Karlsruhe – Leibniz Institute for Information Infrastructure, the database serves as a foundational resource for solid-state chemists, materials scientists, crystallographers, and geophysicists. Established in 1983, with records dating back to 1913, ICSD catalogs three-dimensional structural determinations from the scientific literature. Researchers rely on its curated datasets for crystal structure modeling, high-throughput computational screening, phase identification, and materials discovery.

What it is

ICSD is a specialized crystallographic database focused on completely determined inorganic crystal structures. In structural chemistry and materials engineering, knowing the precise arrangement of atoms within a unit cell is required to predict physical, electronic, magnetic, and thermal properties. ICSD aggregates published experimental and calculated crystal structures, standardizing crystallographic parameters into structured records that can be searched, visualized, and downloaded in standardized Crystallographic Information Framework formats.

Every standard entry in ICSD provides complete structural coordinates rather than summary diffraction peaks alone. This includes unit cell dimensions, space group symmetry, fractional atomic coordinates, site occupation factors, and atomic displacement parameters. The repository supports experimental characterization workflows such as Rietveld refinements and computational initiatives requiring high-fidelity input geometry for density functional theory simulations. To maintain archival integrity, ICSD operates as a certified trusted digital repository holding CoreTrustSeal accreditation.

Who runs it and what it covers

ICSD is produced, curated, and distributed by FIZ Karlsruhe – Leibniz Institute for Information Infrastructure in Germany. FIZ Karlsruhe oversees production, software development, quality control, and licensing, collaborating with the Cambridge Crystallographic Data Centre, the International Centre for Diffraction Data, Technicum Stuttgart, and the Vinča Institute of Nuclear Sciences.

As of late 2026, the database contains 347,985 crystal structures (with release 2026.1 reporting 335,032 verified entries). The collection expands by 12,000 to 16,000 new structures annually through biannual releases. FIZ Karlsruhe indexes records from over 80 core journals and 1,400 broader publications, spanning 117,000 articles across 160,000 authors.

The scope of ICSD covers four distinct structural categories:

Fully determined experimental inorganic structures: Phases where composition is specified and atomic coordinates are experimentally resolved through single-crystal or powder diffraction.
Experimental structures assigned to structure types: Published materials where unit cells and compositions are defined, with full atomic coordinates derived from known crystallographic prototypes (such as perovskite or rocksalt types).
Experimental metal-organic structures: Added starting in 2018, these include metal-organic complexes exhibiting relevant inorganic material properties or applications in catalysis, sensing, and energy storage.
Theoretical inorganic structures: Calculated structures from peer-reviewed literature demonstrating low total energy (E_tot) and originating from methods yielding results comparable to experiment.

ICSD allocates roughly 80% of its entries to over 11,200 structure types. It derives standardized descriptors often omitted in original papers, including Wyckoff sequences, Pearson symbols, and ANX formulas. The curation team applies systematic data curation procedures to verify electroneutrality, elementary cell consistency, and calculated density against reported values, tagging inconsistencies without altering original author publications.

How to search or use it

Researchers access ICSD through the browser-based ICSD Web portal or a local Windows-based ICSD Desktop installation. The ICSD Web interface provides specialized search masks structured to handle chemical, structural, and bibliographic criteria. Follow these seven operational steps to search and retrieve crystal data:

Select the search mode: Open the ICSD Web portal and select Basic search and retrieve, Advanced search and retrieve, or Expert Search. Basic search supports rapid keyword or author queries, while Advanced search divides parameters into thematic modules.
Define chemical parameters: In the Advanced Search “Chemistry” mask, specify elements, stoichiometric formulas, or oxidation states. The interface supports exact stoichiometric queries, element combinations (binaries, ternaries, quaternaries), or excluded elements.
Apply crystallographic and symmetry filters: Open the “Cell” and “Symmetry” tabs to constrain lattice parameters (lengths a, b, c and angles α, β, γ), cell volume, crystal system, Laue class, or specific space group numbers (1 to 230). Fields accept values, lists, and ranges.
Filter by structure type and descriptors: In the “Structure Type” and “Crystal Chemistry” sections, filter entries by Strukturbericht symbols, prototype formulas, Pearson symbols, or Wyckoff sequences to identify isostructural phases across different chemical systems.
Constrain experimental provenance: Use the “Experimental Information” mask to filter by radiation source (X-ray, neutron, electron), measurement temperature, pressure, or crystallographic R-value thresholds. Select between experimental, theoretical, or metal-organic datasets.
Execute and combine queries: Run the search to review hit lists displaying collection codes, compound names, sum formulas, and bibliographic citations. Use the “Query Management” menu (“Manage Queries”, “List Combined Queries”, “Create Combined Query”) to combine searches using Boolean logic.
Inspect, simulate, and export: Open records to view 3D coordination polyhedra and atomic environments. Generate simulated powder diffractograms directly within the platform, validate crystallographic geometry with tools such as checkCIF, and export standardized CIF files for Rietveld modeling or DFT simulations.

Strengths and limits

ICSD offers exceptional utility for materials research while operating under defined technical boundaries:

Curated and standardized data: Each record undergoes algorithmic plausibility checks and expert editorial review. Standardized cell settings enable direct structural comparisons across decades of literature.
Comprehensive historical depth: Continuous cataloging since 1913 ensures access to foundational solid-state literature that pre-dates electronic publishing.
Predictive materials discovery: Integration of curated theoretical structures and calculated attributes (in collaboration with initiatives like the Materials Project) supports high-throughput screening and machine learning.
Advanced query architecture: Granular search masks allowing queries by ANX formulas, Pearson symbols, and structure prototypes enable structural discovery based on symmetry rather than chemistry alone.
Rigid 3D periodicity requirement: ICSD exclusively includes crystal structures that can be completely represented in three periodic dimensions. Consequently, modulated structures, incommensurate crystals, polytypes, quasicrystals, and two-dimensional thin films are excluded.
Commercial subscription access: ICSD is a proprietary resource requiring institutional or corporate licensing fees, which limits open access for unfunded independent investigators.

Alternatives

Researchers evaluate several complementary crystallographic and diffraction resources based on chemical scope, licensing models, and experimental workflows:

Database	Primary Focus	Access Model	Quality Curation	Primary Research Use
ICSD (FIZ Karlsruhe)	Completely determined inorganic and mineral crystal structures	Commercial institutional subscription	Expert crystallographic review and algorithmic validation	Inorganic materials modeling, solid-state chemistry, DFT starting structures
Crystallography Open Database (COD)	Open-access small-molecule and inorganic crystal structures	Open access (public domain / CC0)	Automated format checks; community crowd-sourced	Open science workflows, high-throughput screening without licensing limits
Cambridge Structural Database (CSD)	Organic and carbon-containing metal-organic crystal structures	Academic and corporate subscription (CCDC)	Manual curation and 2D/3D chemical validation	Pharmaceutical polymorph screening, supramolecular chemistry, drug design
Powder Diffraction File (ICDD PDF)	Powder diffraction patterns, d-spacings, and phase identification data	Commercial institutional license	Standardized editorial indexing with quality indicator marks	Routine qualitative and quantitative XRD phase identification

FAQ

How do researchers cite an ICSD record in publications?

FIZ Karlsruhe specifies that researchers using ICSD data should reference the individual record collection code and database release version in the main text of their publication (for example, “ICSD-1234 (ICSD release 2026.1)”) alongside the original primary journal citation. In the reference list, authors should include the canonical methodological reference: D. Zagorac, H. Müller, S. Ruehl, J. Zagorac, and S. Rehme, Journal of Applied Crystallography 52 (2019), 918–925 (DOI: 10.1107/S160057671900997X).

Can ICSD data be accessed through programmatic APIs?

Yes. Institutional and corporate subscribers can license programmatic API access to ICSD. The API enables data scientists to automate queries, extract structural parameters, and pipeline curated crystallographic coordinates directly into machine learning and materials property prediction workflows in compliance with FAIR data principles.

What is the difference between ICSD and COD?

While both databases catalog inorganic structures, ICSD is a professionally curated commercial repository operated by FIZ Karlsruhe featuring rigorous editorial validation, standardization into 11,200 structure types, and extensive coverage dating to 1913. The Crystallography Open Database (COD) is an open-access community repository that accepts organic and inorganic deposits under public domain licenses, offering unrestricted automated bulk downloads with lighter centralized editorial re-standardization.

Does ICSD contain organic or biological macromolecules?

No. ICSD specializes strictly in inorganic compounds, pure elements, metals, alloys, and minerals. Organic molecules and coordination compounds without inorganic material utility belong to the Cambridge Structural Database (CSD), while biological macromolecules such as proteins and nucleic acids are archived in the Protein Data Bank (PDB).

Sources

FIZ Karlsruhe. (2026). ICSD – The World’s Largest Database for Completely Identified Inorganic Crystal Structures. FIZ Karlsruhe – Leibniz Institute for Information Infrastructure. https://icsd.products.fiz-karlsruhe.de/
FIZ Karlsruhe. (2026). Inorganic Crystal Structure Database (ICSD): Product Details and Curation Standards. https://www.fiz-karlsruhe.de/en/produkte-und-dienstleistungen/inorganic-crystal-structure-database-icsd
FIZ Karlsruhe. (2026). About ICSD: Data Curation, Inclusion Criteria, and Citation Guidelines. https://icsd.products.fiz-karlsruhe.de/en/about/about-icsd
FIZ Karlsruhe. (2026). ICSD Web Search Portal and Query Interface. https://icsd.fiz-karlsruhe.de/index.xhtml
Zagorac, D., Müller, H., Ruehl, S., Zagorac, J., and Rehme, S. (2019). Recent developments in the Inorganic Crystal Structure Database: theoretical crystal structure data and related features. Journal of Applied Crystallography, 52(5), 918–925. https://doi.org/10.1107/S160057671900997X