thank you scinikhil
But, I think, to this aim the lipid.rtp file is needed and I can not find it for gromos53a6 which the tytorial is based on.
fortunatly, I found lipids-AMBER-POPC-joakim-v2 pakage that contains all necessary files for lipids such as lipid.rtp, atomtypes.atp, forcefield.itp and fnonbonded.itp. so I combined this files with the corresponding files in the amber99sb-ildn force fileds and run the md as a normal method using this new forcefield.
every thing sounds good.
I would like to know is it right? Are have the same experience?