You are seeing this page because we have observed unusual use of this service from this network.

Access Structures, provided by the Cambridge Crystallographic Data Centre (CCDC), is a web service that is freely available to all scientists. It is provided for the rapid lookup of crystal structures in the Cambridge Structural Database (CSD). This free service is linked to by many scientific publishers, providing easy access to structures reported in the literature. It also provides a vital service for reviewers of new manuscripts, increasing the quality of crystal structure information in the public domain. The service is extensively used by scientists around the world who rely on it for their research and is a core part of the infrastructure supporting crystallographic research worldwide.  The CCDC is a University of Cambridge Partner Institute and is a charitable organisation, funded and governed by the crystallographic community. We provide these free services as part of our charitable mission. 

The unusual use we are seeing from your host may have the potential to impact on the availability of these services to our other users around the world. Our service has been designed and optimised to respond to requests for small numbers of entries from a large number of users. It is not designed or intended to be used for extensive data mining or to be used programmatically. We have developed other more sophisticated tools that are widely available and enable users to do this.  

If you would like to undertake systematic searching, retrieval and analysis of crystal structures then this can be done through the CSD System which also provides for advanced programmatic access through a powerful Python API. The CSD is extremely widely used and may already be available to you at your institution through one of many national or regional access agreements. If this does not fulfil your needs then we are happy to discuss other ways in which we can help the CSD advance your research.

We would therefore like to learn more about the nature of the use of this service so that we can help provide you with a more effective way to access the data you need. 

For more information about our data access policies and terms and conditions for use of Access Structures, please read about this service. These policies are in place to allow us to maintain free services and ensure that our ability to make data widely available to the community is not compromised.

If you would like more information on the CSD System or you would like to discuss research opportunities, please contact us through our Enquiry Page.

Alternatively, to restore your access to this service please contact us directly on, explaining that you have seen this page.