Electron Diffraction Data in the CSD

In recent years, we have noticed an increase in the number of structures deposited to the Cambridge Structural Database (CSD) that are measured with electron diffraction techniques. As of the beginning of 2020, approximately 50 electron structures have been added to the CSD. Since this field of research is rapidly developing, we thought it timely to investigate all the electron studies in the database to ensure they can be easily located and have worked to identify any structures that were missed during the initial data curation process.

 

A graph showing the number of structures measured with electron diffraction added to the CSD between 2015 and 2019

  

The CSD is made up of many different types of experimental crystallographic data. When structures are added to the database our Scientific Editors curate the data and record important aspects about the structure, such as if any specialist techniques were used, in a consistent way – allowing our users to search for these structures in our software.

Our data curation software checks information in certain CIF fields to automatically identify some types of studies, including electron diffraction. However, this relies on identifying information being included in the deposited data in a standard place. This can be a challenge with new techniques as the standards may not be defined. We are investigating where ‘identifying information’ is included in CIFs in order to work to improve our automatic identification tools; further information about these investigations are detailed in a recent blog post. Labels can also be added to the data manually – if one of our Scientific Editors identifies an electron structure during the curation process.

 

Image of Refcode WOFXEX, a structure determined with electron diffraction available in the CSD

 

To assist scientists with the deposition and location of data from electron diffraction structures and other specialist techniques we have created a series of FAQs:

These FAQs include instructions on how to find the data from these sources in the CSD alongside what information we would recommend including in the deposited data. As part of a CSD Improvement Project, we have also been improving our labelling of structures measured with neutron diffraction techniques or synchrotron radiation.

 

Future work

We are currently working to evolve our underlying database and associated systems and therefore we hope to be able to enhance our deposition processes and provide more options for you to recognise this type of structure and filter on these structures in the future.

We are also working to locate more structures and create processes to deal with other types of non-standard data, such as multipolar refinements. We would be keen to know of additional information you would like to see labelled in the CSD.

For more information about what data can be deposited into the CSD, please see our Deposit a Structure page.