[lammps-users] Some questions about "displace_atoms"

I think maybe there is a bug in LAMMPS, because the "displace_atoms all ramp z 0 lz/10 z 0 lz" doesn't make any error during the simulation, even though the "lz" in it means nothing (well, I think it may mean zero for I tried to substitute it for 0, the result is the same). In addition, if I change "lz" with other signals but number, such as "displace_atoms all ramp z erw nhj z pxz hbgf", where "erw", "nhj", "pxz", "hbgf" are all totally random staff on the keyboard, the LAMMPS doesn't think it an error, and seemes to take them all as zero.

When LAMMPS is doing input, it doesn't check that every quantity
that is supposed to be a number is in fact a number and not a text
string, like lx or pzz. It will just try to read it as a number and get 0.

If you want lz/10 to be turned into a number to use as a command
argument, then you need to use a variable. See the doc page for
variables.

Steve