Dear all,


I was wondering whether the tool available through CSD-Materials on Mercury to screen potential co-crystal components by molecular complementarity is available on the CSD Python API and, if so, how this tools could be accessed.


Thanks for the help!



Dear Luca,

this functionality has been exposed in the CSD Python API, but is currently available only to Research Partners of the CCDC. I believe you are working for Merck at the moment, and they are a Research Partner.  In which case you will be able to download the ccdc_rp package from the Research Partner Portal at CCDC, and gain access to it via

from ccdc_rp.descriptors import MolecularDescriptors
complementarity_screen = MolecularDescriptors.ComplementarityScreen()

I hope this is helpful.  Please get back to me if anything is unclear.

Best wishes


Thanks Richard! I was able to install ccdc_rp. 


However when I try to run a calculation, I am not sure how to get the results from it. 


What I did was:


complementarity_screen = MolecularDescriptors.ComplementarityScreen(), [mol2]) (where mol1 and mol2 are two molecule objects)


When I try to get the results however:


I get

<property at 0x2e396fa64a8>
And I don't know how to actually extract a value from this object.
Am I missing something?

Hi Luca,

the return value of the screen() method is a ComplementarityScreen.ResultSet.  This has a couple of methods for extracting results grouped by active or by coformer, and list-like access to individual results, i.e.

results =, [mol2])

result = results[0]

Then you can get the individual success property:




There is documentation for the ccdc_rp package available on the downloads page of the CCDC,

under the CSD Python API Research Partner Add on documentation.

I hope this is clear.  Get back to me if you would like more information.

Best wishes


Hi Richard,


Thanks a lot, that worked! 



Hi Richard,

I am trying to install the rp package using the instructions in "CSD Python API 3.0.4 Research Partner Module Documentation" and have not been able to successfully install it. Could you please advice? Here are my observations:

1) Installed csd-python-api (Python 3.7 CSD Python API 3.0.4 conda package (Windows 64-bit) ):

conda install -c "C:\Users\stthomas\ccdc_conda_channel" csd-python-api (link to log)


2) Installed csd-python-api-rp (Python 3.7 CSD Python API 3.0.4 Research Partner Add-on (Conda, Windows))

conda install -c "C:\Users\stthomas\ccdc_rp_conda_channel" csd-python-api-rp (link to log)



Stephen Thomas

The ability to rationally design and predictably construct crystalline solids has been the hallmark of crystal engineering research. To date, numerous examples of multicomponent crystals comprising organic molecules have been reported. However, the crystal engineering of cocrystals comprising both organic and inorganic chemical units is still poorly understood and mostly unexplored. 




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