qeq in LAMMPS

Hi All:

I am a newer here. My experience on MD simulations is focused on DL_Poly. I heard in LAMMPS, charge equilibration method is implemented, which is also I needed for my Ph. D thesis. After look at the documents throughly, I found that:

Charge equilibration method appears at two places: COMB and REAX.

Elements in COMB are limited to " for Si, Cu, Hf, Ti, O, their oxides and Zr, Zn and U metals. "
Elements in Reax are limited to " The default ffield.reax contains parameterizations for the following elements: C, H, O, N, S. "
I am not so sure if I omitted some useful information. Welcome to correct me!

In my system, there are six elements: Al, O, N, C, H form a molecule; Cobalt as a metal.
So, my question is, how can I simulate this kind of system using LA

If all you want to do is QeQ, then you can use fix reax/qeq by
itself, on whatever charges you have defined. The question
of the non-Coulombic part of the force field is up to you. You
can use ReaxFF or COMB or something else. Obviously
you'll want to use a FF that has Co parameterized for your system.


thanks for your reply! what do you mean exactly by “use TeaxFF or COMB or something else”? Is it possible to use any kind of force field , for example UFF, along with qeq in LAMMPS?

many thanks!

It's possilbe to use any force field that LAMMPS has with
fix qeq/reax. Not so with fix qeq/comb which can only
be used with the COMB ff.