[Cod-bugs] Programmatic Access to COD Data for Acentric Structures

[Andrius Merkys]

Dear Jason,

On 2025-05-29 16:25, Jia, Qiming wrote:
> I’m a research student currently working on a project that requires 
> downloading and processing crystallographic data from the COD, 
> specifically focusing on non-centrosymmetric (acentric) structures for 
> machine learning purposes.
> While trying to automate the search using |search.php|, I encountered 
> difficulties—my script expected JSON responses, but it seems this 
> endpoint is not designed for API use. I’ve explored the documentation 
> but couldn’t find a confirmed method to programmatically filter or 
> retrieve structures based on space groups or symmetry properties.

Please refer to COD Wiki page on the usage of search API [1]. You can 
use result.php as an endpoint emitting JSON-formatted output. You can 
query on Hermann-Mauguin space group symbol or space group number. I 
believe this should work in your case, you will just have to query for 
all acentric space groups separately.

You may as well use COD OPTIMADE [2] interface, its base URL is at [3]. 
Be sure to use v1.2.0, as prior to this version there were no 
symmetry-related properties supported by OPTIMADE standard.

Hope this helps,
Andrius

[1] https://wiki.crystallography.net/RESTful_API/
[2] https://www.optimade.org
[3] https://www.crystallography.net/cod/optimade/v1.2.0/

-- 
Andrius Merkys
Vilnius University Institute of Biotechnology, Saulėtekio al. 7
LT-10257 Vilnius, Lithuania

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