[lammps-users] running with different NVT fixes

It makes no sense to deform (e.g. stretch) the simulation
box for a non-periodic system. The only thing you can do
is to pull on a subset of atoms at each end of the wire
and move them apart (and the box will follow). You can
do this in various ways. E.g. fix move, or set the end
atoms with an initial velocity and turn off the force on them.

Steve