About the ReaxFF ffield.reax

LAMMPS LAMMPS Beginners
1

Hello to all,

In mannual, I see that there is default ffield file “ffield.reax” in Potential file. But I cannot find it in the latest stable version of LAMMPS.

Where can I find this file. Really appreciate for your kindly help!

Sincerely,
Shusen Guo

2

They … look like they’re still there? Like this one?

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3

ReaxFF potential files are very specific to a given type of system and thus you cannot just use any potential file for any application. Even if the file has entries for all the elements you need, it may not be usable, since many of the people that parameterize such potential files have a tendency to re-use old parameter files and just update those entries relevant to their work.

Thus, it is required that you first carefully study the published literature for a ReaxFF parameterization that is suitable for your specific application. The parameter files that are bundled with LAMMPS rarely are applicable and represent only a very small sample of the pool of available potential files and parameterizations.

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4

Hi, srtee

Thanks for your help. In mannual, there maybe a default ffield.reax file without label. The default ffield.reax describes interactions between C H O N

5

Hi, akohlmey

Really appreciate for your help! In each ffield.reax.label file, I have found the relevant literature about the force field. In mannual, I have observed that the default ffield.reax(without label,such as ffield.reax.cho) can describe the interactions between C H O N. Thus, I have searched this file in the potential file. But I cannot found it. Maybe I misunderstand the mannual. Or this default ffield.reax has been deleted from the source files of LAMMPS.

Sincerely,
Shusen Guo

6

There is no “default” ReaxFF potential file and there never was. As already stated, parameterizations are defined by the publication describing it. So if you are referring to a specific parameterization, you have to name its publication.

7

Hi, akohlmey

Thanks for your help, I will read the relevant literature as you suggested.

Best regards,
Shusen Guo

8

But the documentation mentions it:

LAMMPS provides several different versions of ffield.reax in its potentials dir, each called potentials/ffield.reax.label. These are documented in potentials/README.reax. The default ffield.reax contains parameterizations for the following elements: C, H, O, N.

Link: pair_style reaxff command — LAMMPS documentation

9

This block of text seems to go back to the old, obsolete, Fortran based ReaxFF implementation in LAMMPS and the times when there were just a couple of parameterizations available (all for combustion reactions, if I remember correctly). I will remove/edit it, since it is misleading people into thinking that ReaxFF parameterizations can be treated as if they were using quantum mechanics.

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