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Re: [lammps-users] Inelastic collisions in atom_style hybrid sphere dipole
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Re: [lammps-users] Inelastic collisions in atom_style hybrid sphere dipole

From: Ashwin Padmanabhan <ashwinpadmanabhan95@...24...>
Date: Tue, 27 Jun 2017 12:25:33 +0530

Respected Dr. Plimpton and Dr. Kohlmeyer,

Thank you so much for the help. I deeply appreciate it.

Warmest Regards,
Ashwin Padmanabhan.

On 24 June 2017 at 20:05, Axel Kohlmeyer <akohlmey@...24...> wrote:

On Sat, Jun 24, 2017 at 10:26 AM, Steve Plimpton <sjplimp@...24...> wrote:
There are a couple options, none of which may
be exactly what you want:

a) there are granular potentials that include an attractive
force (like JKR potential), so that particles will "stick"
together when they collide.  We have one of these
internally, but it hasn't yet been released in LAMMPS.
There may be one in LIGGGHTS which is built on top
of LAMMPS, and you can google for it.

b) LAMMPS can model rigid bodies composed of
multiple granular particles, e.g. dimers.  But you
need to start with a set of rigid bodies, or pour them
into a box, etc.  See the fix rigid/small and fix pour commands.

There is no option currently in LAMMPS to convert colliding
particles into rigid bodies on the fly.

​perhaps not rigid, but to have particles stick together and not come apart could be modeled with adding (harmonic) bonds using fix bond/create. without source code modifications, that would only work for a monodisperse system​, and it would make the input quite complex and tricky (use atom style hybrid with bond added; reserve space for a sufficient number of bond types, bonds per atom, specials per atom; use special_bonds lj/coul 1.0 1.0 1.0 and possibly more tweaks).  

i have a vague recollection, that something like this was discussed on this mailing list before (w/o dipoles), so perhaps a careful dig into the lammps-users mailing list archives might help.


> I deeply apologize if I have offended you in anyway.

you haven't.  You're just asking Qs and getting advice.
Now you have some work to do, to figure out an appropriate model.


On Sat, Jun 24, 2017 at 4:43 AM, Ashwin Padmanabhan <ashwinpadmanabhan95@...24...> wrote:
Respected Sir,

I think this would answer my all my queries- Is coalescence of two particles possible in Lammps under the Granular model?
Im sorry if these questions seem very basic.

I deeply apologize if I have offended you in anyway.


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Dr. Axel Kohlmeyer  akohlmey@...33....24...
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.