The steps I had done:

1. I built box with pretty far distance from the outer surface of protein to the box side (-d = 20.0 A), and I thought this size had been too big for average distance used for box size

2. I used the box volume as a reference volume in input files for packmol. I also used the amount of water solvated in box as my reference to solvate my protein in packmol. I build an amylase enzyme in 5M NaCl system (which was a high salt concentration)

3. Then, the output pdb file from packmol I executed in energy minimization, but the potential energy was still so extremely high (~ +10^5)

4. I was in doubt with the concentration of salt ions within the system, and at the same time I was not sure with the box size.

is there any command in gromacs or any software able to help me get through this super high energy minimization? how to ensure the concentration of salt added to the system in the right amount?

thanks in advance