[gmx-users] ligand problem

[kiana moghaddam]

Hi gmx-users 
I'm going to study the molecular dynamics of DNA-ligand interaction. I prepared the DNA topology by using the parmbsc0 force field and the ligand by the GAFF force field. 
My question is: what level of theory (HF/6-31G* or B3lyp/6-31G*) is needed for RESP calculation?
can someone help me to address this problem?
 
Best Regards  
kiana