Dear lammps users,
I have came across this ERROR massage more than once, and unfortunately I have not found information about it in the manual.
Please see the screenshot below:

which parameter is incorrect?
I have changed “z -30 30” to “z 30.0 30.0”, but it doesn’t work.
Thank you so much!
Best wishes.
michelle
Dear lammps users,
I have came across this ERROR massage more than once, and unfortunately I
have not found information about it in the manual.
Please see the screenshot below:
which parameter is incorrect?
I have changed "z -30 30" to "z 30.0 30.0", but it doesn't work.
that is because that is not the problem. ramp command does not accept
variables, so v_velocity is causing the problem.
the manual states explicitly, where variables are allowed. everywhere else,
they are an error. this can also *very* easily tracked down by building a
command line in stages.
axel.

The problem has been solved. I didn’t find it in the error part, and I really need to read other parts more carefully.
I have been using lammps to do MD simulation for only months, so I have not master commands sufficiently . it’s a try-fail-try process.
Hope to learn more from your sincere help.
Thank you very much!
Best wishes.
Michelle
