[lammps-users] How to realize unloading?

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1

Hi everyone, I am doing the tensile test. I want to first enforce
tensile force on the nanowire, then unload it.

I have tried to use fix deform erate command. However, when I set the
erate <0, the following error occurred.

ERROR: Final box dimension due to fix deform is < 0.0
What is the meaning of this error?

So what is the correct way to unload after tension? Many thanks for any advice?

Best wishes,

Han

2

Here is the code that triggers it:

    } else if (set[i].style == ERATE) {
      set[i].lo_stop = set[i].lo_start -
  0.5*delt*set[i].rate * (set[i].hi_start-set[i].lo_start);
      set[i].hi_stop = set[i].hi_start +
  0.5*delt*set[i].rate * (set[i].hi_start-set[i].lo_start);
      if (set[i].hi_stop <= set[i].lo_stop)
  error->all("Final box dimension due to fix deform is < 0.0");

You can see that you are running long enough at a high enough rate
that your box size will shrink past 0.0. Not good.

Steve