Different Pairwise Interactions between the Same Type in Different Regions

Dear LAMMPS Users

I am sorry to disturb you.

I am writing to ask, for the same atom type, if there is a way to turn on one type of pairwise interaction only when they enter a certain region of the box, while they interact via a different type of pairwise interaction outside the region?

Thank you very much for your patience.

Best Wishes
Lunna

You would have to break down your simulation into a loop over short segments and in between set atom types based on region. But please note, that any discontinuous change of the potential for any atom is very problematic.
Axel

Dear Axel

Thank you very much. I understand it is not a very physical scenario to simulate and I will be careful with its meaning if I can set the model up.
Can I get some hint on how to “set atom types based on region” - I think I might need to use “set type” and “region” and probably “variable” but I cannot get my head around.

Thanks.

Best Wishes
Lunna

Dear Axel

Thank you very much. I understand it is not a very physical scenario to simulate and I will be careful with its meaning if I can set the model up.
Can I get some hint on how to “set atom types based on region” - I think I might need to use “set type” and “region” and probably “variable” but I cannot get my head around.

if you cannot figure it out, then you are out of luck. i have no time or interest to go beyond giving you the generic suggestion i did. you would indeed need the set command and possibly an hybrid pair style.