accepted force field deviation

Dear Lammps users,
I am using CHARMM optimized force field for my molecule. The article that I used for extracting force field parameters used NAMD. I am running with Lammps at the exact same condition of PVT as the article, but there is still a little deviation between 1 and 2 percent at the resulted density. I wanted to know how much deviation is accepted and shows that the simulation is the same as the article?

Best regards