[gmx-users] A promblem when use the x2top

[Hanming]

Dear All, 

I have a very big polymer molecule and try to use x2top to generate a .top
file. After I relax the molecule and minimized it by other MD and MM
software , get a .pdb file to do as the input for the x2top. But an error
always come out like this
"Fatal error: No forcefield type for atom C6 (1346) with 2 bonds" 

I tried small molecules they are all Ok. But when meet the big one ,error
always come out. Can I get some suggestion from you about this problem? 

Thanks a lot. 

Ming