"Pair_style body/nparticle" command

Hello everyone,
I’m using LAMMPS to compare the thermodynamic performance of a pure CaO material and same material added with nanoparticles. Particularly, for the material added with nanoparticles, I used the commands:
atom_style hybrid charge body nparticle 5 12
pair_style body/nparticle 2.5
The simulation ran successfully. My query is, I want to specify the type of “nparticle” since I will be using different kinds of nanoparticles (like silica and alumina) in the material. LAMMPS documentation gives no details about this. How can I specify the ID of “nparticle”? Can anyone help please?

The nparticle body style is not a suitable solution for this type of simulation and the pair style does not model the interactions correctly.

What interaction potentials do you want to use?

Thanks Akohmey for your response. I’m using Lennard-Jones potential.

You cannot use only Lennard-Jones for your material. At the very least, you will need LJ + Coulomb. But there are also potentials using Born+Coulomb or LJ + Coulomb + Bonds/Angles.

Pair style body/nparticle will compute only the same interaction as lj/cut, but not coulomb and also all parameters for all particles will be the same, which is obviously not suitable for your system.

Thanks alot Akohlmey! This is helpful indeed. Will review it.

My guess is that you got distracted by the “nparticle” name. This has actually nothing to do with nanoparticles but rather stands for (literally) “N particles”. This pair and body style was implemented as a “demo” to debug the body atom style interaction. As already explained in the body style howto, the same model can be (better) modeled with the lj/cut pair style and fix rigid/small. More complex models are expected to be implemented like the rounded/polyhedron style.

Basically, you will need to use an atom style like “charge” or “full” and then can read in your substrate from a data file or create it by defining a region and then use the create_atoms command on it (multiple times for multiple atom types). Same for adding nanoparticles. Easiest is usually to generate the entire system with external tools and then just import it as a data file. Building inside LAMMPS as mentioned is also possible, if you study the docs more carefully and then you could import small objects, if needed multiple times, by using the molecule command and then create_atoms with the mol keyword.

Much appreciation Axel.