Compute rdf use groups instead of atom types

LAMMPS LAMMPS General Discussion
1

Hello

It seems that in many machine learning force fields each element in the simulation has one atom type, regardless of whether the element appears in different molecules. So, if carbon is present in four different molecules, it is the same atom type in all these molecules. This makes it a bit tricky to use compute rdf to obtain radial distribution functions for different molecules/atoms/ions in a system, as the atom type in a molecule will also be used in other molecules in the system. Would it be possible to use groups instead of atom types in the compute rdf command? If someone has any good ideas to achieve what I want to (obtain RDFs for different molecules containing the same elements and atom types), I would be grateful.

2

What is stopping you to assign the same element to multiple atom types?

3

Good question. Probably my lack of knowledge. I thought that perhaps the force fields were set up such that the atom types would be linked to the parameters. But now I realize that they are set up using the atomic weights or element names, which is of course a much more logical way. Anyway, thanks for the help!