Dear experts,
please have a look into the link

http://iopscience.iop.org/article/10.1088/1361-651X/aa584f/meta
 Actually i want to make membrane using ZIF-8 with PDMS polymer. 

I created a polymer structure using build module with 25 repeating uints and from CCDC website i downloaded the ZIF-8 structure as mentioned in the above paper. the author used different number of zif-8 atoms with PDMS to make a membrane. my question is how can we use specific number of atoms from structure downloaded from CCDC website? 

i tried to make structure P1 then copy the number of atoms i needed but when i do optimization of those atoms it fails . i tried to contact the author but author isn't responding me.

i hope i am able to make you guys understand what i want to know and what problem i am facing.

in brief, i want to make PDMS membrane in which specific percentages of ZIF-8 i want to use.????

looking for proper guide line from the experts 

thank you