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Re: [lammps-users] Is it possible to realize the “soft” body particle in LAMMPS?
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Re: [lammps-users] Is it possible to realize the “soft” body particle in LAMMPS?


From: Wusheng Zhang <minky.k.jiang@...24...>
Date: Wed, 6 Sep 2017 09:01:28 -0400

Hi Axel,

Connecting the "outer" particles with the large central particle by bonds sounds reasonable and easier. Thank you very much!

Best regards,
zjgbz

2017-09-05 21:45 GMT-04:00 Axel Kohlmeyer <akohlmey@...24...>:


On Tue, Sep 5, 2017 at 9:15 PM, Wusheng Zhang <minky.k.jiang@...24...> wrote:

Dear LAMMPS users,


I intend to completely cover a large sphere with lots of middle size spheres - name it as cluster. And the small spheres fill in the other space of the simulation box. On one hand, these middle size spheres cannot leave the large sphere, so the “body particle” might be applicable.

​at the moment, there is no significant benefit for the setup you describe in using a body particle over ​using fix rigid (or any of its variants). the only integrator that exists is equivalent to fix rigid. for more complex operations, e.g. bodies that can be deformed, you will need to write a custom integrator (and come up with a suitable model/theory for the equations of motion of that).

But on the other hand, I also need to measure and tune the Young’s module of the cluster by compress the simulation box. In this sense, I hope that I can tune the interaction between the middle size spheres and the large sphere, and this is not applicable if I set the cluster as a body particle. So is it possible that I can set the cluster as a kind of body particle but I can tune the interaction between the middle size spheres and the large sphere? Thank you very much.

​if you have a rigid object, there is nothing to tune but the non-bonded interactions of the constituent particles​.

on the other hand, you could also model the kind of system you describe, by having all your "outer" particles connected with the central particle through an explicit bond. then the force constant of that bond would determine how easily your particle can be deformed. depending on how "fluid" you want the particles on the surface to be, you could have them only interact via non-bonded interactions, or use a "mesh" of bonds, there as well.

​axel.​


 


Best regards,

zjgbz


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--
Dr. Axel Kohlmeyer  akohlmey@...24...  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.