Hi every one,

I made a funtionalized graphene with 3 functional groups (-COOH, -OH, -CO), and then I used "calculate bond types" in Material Studio. But after using "calculate bond types", there were some errors with geometry optimization (forcefield: pcff). In detail:

Unable to calculate the ForcefieldType for particle 'C'
The typing engine has been unable to assign a forcefield type.
No typing rules found that match (except the wildcard '?').

Could you explain why there are some errors here? Thank you very much.

If possible, could you provide functionalize graphene model? 

Thank you.