Applying external stress of 5 GPa on the walls of a box containing atoms in LAMMPS

Dear LAMMPS users, Can anyone please advise me on this LAMMPS related problem. I want to apply a pressure of 5 GPa (from all x,y,z directions) on a box containing almost 20000 atoms. I got to know about fix deform command but it seems that it takes only strain as input but I want to give Stress as input. For more information, this problem is related to forming nano-glass from nano particles where we have to apply pressure on many spherical nano particles contained in the box. After applying pressure I want the atoms to be squeezed together inside the box and form metal-glass.

It seems that this previous post contains several suggestions that you could apply to your problem.

Why not fix npt?