system not stable

Hello,everyone ,this is rufer,I build a system with a diamond semi-sphere slip on a diamond substrate.but when I give a pressure in -z direction to sphere to press them together,it will not works well,the sphere is bouncing up and down ,and the system is not stable,so can anyone give some advice? any advice will be appreciated.

Kind regards

Rufer

here is my in scripts

C.Tersoff (150 Bytes)

minimize.in (2.82 KB)

press-test.in (1.83 KB)

LAMMPS will strictly follow the physics of the model you implement, it
doesn't know anything about what your intentions are.
Your input deck is far too complex and too convoluted to quickly give
you some meaningful advice, and a proper line-by-line and
feature-by-feature debugging is *your* job, not ours.

thus the best advice I can give you is to a) simplify your input, and
b) remove all unnecessary parts and also the parts where you are
applying the force to the mobile atoms. then you can make certain that
the system is acting the way you would expect for that setup. next you
can go about re-adding the force that should move atoms.

one more comment. you seem to be using a force that is dynamically
computed from system properties. that can lead to feedback and thus
oscillations like you are describing. you may need to do something
more sophisticated in that regard, like what is possible using fix
controller, or just stick with a fixed force for the time being. i
repeat, what you see is the physics of what you ask for. LAMMPS is a
computer software strictly following the "rules" of what you define in
your input. so if you do not get what you expect, the cause is that
those "rules" may not be suitable or do not represent the physics of
the system you want to model, or that your expectations and
assumptions are not correct.

axel.

谢谢你的澄清。

Axel Kohlmeyer <[email protected]> 于2020年7月31日周五 下午8:29写道: