[gmx-users] 5' phosphate of RNA

[Mohammad fat habadi]

DEAR Users
I have a RNA that has phosphate(P,OP,OP2,OP3) on 5’.
IN RNA and DNA, 3’ has phosphate and 5‘ doesn’t it and for this all Force fields don’t know phosphate atoms on 5’ of RNA.
pdb2gmx  make an error.
IF I delete 5’ phosphate atoms, I don’t have any problems.  
How can I solve this problem without deleting 5’ phosphate.
regards