Origin of Ni-O (and other) parameters in ffield.reax.FC

LAMMPS
1

Hello,

I’m working on ReaxFF MD simulations of nickel nanoparticles in C/O2 environments.

The file potentials/ffield.reax.FC distributed with LAMMPS (https://github.com/lammps/lammps/blob/master/potentials/ffield.reax.FC). has the following header:

DATE: 2013-06-28
CONTRIBUTOR: Aidan Thompson, [email protected]
CITATION: Singh, Phys Rev B 87, 104114 (2013)

This citation only covers the C-F-H parameterization (Singh et al.). However, the file contains parameters for 10 species (C, H, O, N, S, F, Pt, Cl, Ni, X), so it is clearly a combined/merged force field assembled from multiple sources.

I was able to confirm numerically that the Ni and Ni-C-H block in this file is an exact match to:
Mueller, J. E.; van Duin, A. C. T.; Goddard, W. A., III. “Development and Validation of ReaxFF Reactive Force Field for Hydrocarbon Chemistry Catalyzed by Nickel.” J. Phys. Chem. C 2010, 114, 4939-4949.

However, I have not been able to identify the source of the Ni-O bond parameters. I compared them against:
Zou, C.; Shin, Y. K.; van Duin, A. C. T.; Fang, H.; Liu, Z.-K. “Molecular dynamics simulations of the effects of vacancies on nickel self-diffusion, oxygen diffusion and oxidation initiation in nickel.” Acta Mater. 2015, 83, 102-112.
but the numerical values do not match.

Does anyone know the correct reference(s) for the O, N, S, Pt, Cl, and especially the Ni-O parameters in ffield.reax.FC? Any pointer to whoever originally merged these parameter sets into this file would also be very helpful.

Thank you in advance for any help,
Abderrazak

2

Your conclusion is not correct. What usually happens is the following: when people create a new parameterization for ReaxFF, they start by re-using an old parameter file and then just change entries as needed. Everything else must be ignored. The fact that you were able to identify the origin where the template has been taken from does by no means confirm that those are combined parameters that have been tested. In short, if the publication for a ReaxFF parameter file claims that it has been parameterized for a given list of elements (and a given set of compounds built from those elements and given range of thermodynamic conditions) then that is all that you can use, nothing else.

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3

Thank you so much,

The question is how to do to justify the use of the potential parameters in this file on Ni/O/C, from where we should cite it knowing that the paper is about F/C/H?

4

I just explained that you MUST NOT USE THEM. Please read my explanation again.

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