deltaH for bong breakage ReaxFF

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1

Hello lammps and reaxff users,

I’ve minimized a single molecule (reactant) and same molecule but with one NO2 group removed. (C-NO2 homolysis).

I’ve checked the difference between potential energies of the two molecules (reactant and product) and it’s about 6 times larger than DFT calculated deltaH value for this reaction.

I’ve probably missed something here, because the force field i’m using is trained against this type of molecules and shows a good reproductive ability with similar molecules.

I’m using the si units system so the energy is kcal/mol. Maybe the units of kcal/mol mean something different than kcal/mol_molecules, so a normalization is required ?

David Furman, MSc. student
The Fritz Haber Research Center for Molecular Dynamics
Institute of Chemistry
The Hebrew University of Jerusalem
Jerusalem, ISRAEL

Phone: +972-8656-8909

2

I'll let Aidan comment on the ReaxFF part.
You mention SI units. I assume you don't
mean SI units in LAMMPS since I don't
know why you would use that option for
atomistics. The SI unit of energy is not Kcal,
it's joules, which is a factor of about 4.2x different.

Steve

3

Hey Steve,
I'm sorry, I meant the unit system is 'real'. so the energy units are in
'kcal/mol'