Space groups P1 and Cc: how are they doing?

Area of Science:

• Crystallography
• Materials Science
• Data Science

Background:

• Accurate crystallographic data is crucial for scientific advancement.
• The Cambridge Structural Database (CSD) is a key repository for crystal structure information.
• Historically, some structures have been described using space groups of lower symmetry than appropriate, potentially impacting data interpretation.

Purpose of the Study:

• To assess trends in the use of low-symmetry space group descriptions in the CSD.
• To quantify changes in the frequency of inappropriate space group assignments over time.
• To compare these trends for specific space groups, notably Cc and P1.

Main Methods:

• A survey of recent entries in the Cambridge Structural Database was conducted.
• The percentage of structures described in space groups of inappropriately low symmetry was calculated.
• Data was analyzed for specific space groups, including Cc and P1, comparing current data with early 2000s entries.

Main Results:

• The overall percentage of structures with inappropriately low symmetry descriptions has decreased.
• For space group Cc, this percentage has fallen from approximately 10% in the early 2000s to less than 5% currently.
• For space group P1, the percentage of structures with inappropriately low symmetry descriptions remains largely unchanged, close to 8%.

Conclusions:

• There has been a positive trend in improving the accuracy of space group assignments in crystallographic databases.
• While significant progress has been made for some space groups like Cc, further attention is needed for others, such as P1.
• Continued monitoring and refinement of data deposition practices are essential for maintaining the integrity of crystallographic databases.