[lammps-users] Reduce the error of "Minimize"

I am using a May, 21, 2008 version LAMMPS.

I want to minimize the energy of a group of atoms. I set the ftol, maxiter and maxeval (which are parameters for minimize command) to a reasonable value. But the result of the model after relaxation shows that there are forces about 1e-5eV/A in x, y and z direction for most atoms. However, the force on atoms after relaxation should be about zero. I want the residual force to be less than 1e-9ev/A. How can I reduce the error of force?


I've seen this before. I think it has to do with
the potential. If moving the atoms a distance epsilon (1.0e-16)
does not result in reducing the energy, then the minimizer
can't move the atoms. This can happen even when forces
are not epsilon. E.g. 1.0e-6.