Search for missing symmetry in the Inorganic Crystal Structure Database (ICSD)

Area of Science:

• Crystallography and Materials Science
• Solid-state Chemistry
• Database Curation

Background:

• The Inorganic Crystal Structure Database (ICSD) is a critical resource for crystallographic data.
• Accurate space group assignment is fundamental for understanding and predicting material properties.
• Previous analyses have not exhaustively re-evaluated symmetry for large ICSD datasets.

Purpose of the Study:

• To systematically search for and identify entries in the ICSD with potentially higher symmetry than currently reported.
• To assess the implications of corrected symmetry assignments on material properties, particularly noncentrosymmetry.
• To propose enhancements to the ICSD for improved data accuracy and utility.

Main Methods:

• Conducted an exhaustive symmetry search across 223,076 entries in the ICSD (2023-2 release).
• Analyzed identified entries to determine if a higher symmetry description is applicable.
• Investigated the relationship between noncentrosymmetric and centrosymmetric space group assignments for affected entries.

Main Results:

• Approximately 0.65% of the analyzed ICSD entries were found to be describable by higher symmetry.
• Of the entries identified as noncentrosymmetric, approximately 74% could be accurately described by centrosymmetric space groups.
• These symmetry discrepancies have significant implications for predicting and understanding compatible physical properties of materials.

Conclusions:

• A notable fraction of ICSD entries may be reported with suboptimal symmetry, impacting materials science research.
• The high percentage of noncentrosymmetric entries reclassifiable as centrosymmetric highlights potential errors in symmetry determination.
• It is recommended that information regarding the correct, highest possible space group be incorporated into the ICSD for enhanced data integrity.