Is it possible to realize particles with two, four or six "interaction sites" or "patches"?

Dear LAMMPS users,

I intend to create particles with several “interaction sites” or patches and observe the self-assembly. More precisely, for example, to two “interaction sites”, I hope that any particle in my system can just have two “interaction sites” at their poles. Any two particles can only attract each other at their poles. Hopefully, the randomly distributed particles will finally align to a long chain while they connect with each other at the poles. The attractive force of the pole is short-ranged, and cannot overlap.

If I consider that the two interaction sites are along the x axis, then in the case of “four interaction sites”, the two more interaction sites will be along the y axis, and in the case of “six interaction sites”, the two more interaction sites will be along the z axis. And the interaction in any “interaction site” is the same as the description in the first paragraph.

So is there any way to realize this kind of polar or quadrupolar or hexapolar particles in LAMMPS?

Thank you in advance.

Best regards,

Probably. I think the most straight-forward way to do it would be to form a rigid body that consists of one big particle and has smaller ones embedded at the surface. Then you can make the big particles purely repulsive with respect to other big particles and have the smaller ones do the attraction. I’m sure there must be publications in the literature of such models and their self-assembly.

You can look in the literature for “patchy particles” which

are rigid bodies made of small particles, where patches

of the small particles have different attractive/repulsive

properties based on their LJ cutoffs. They will indeed

self-assemble into interestings structures and phases.

Look for papers from Sharon Glotzer’s group (U Michigan).

Those kinds of models can be setup and run with LAMMPS.

You can also look at the atom_style body in LAMMPS which

allows you to define a single particle with internal structure.

You could write a pair style that used those particles and their

orientation to define whatever interactions you want between

2 body particles.