Hello dear friends,
I want to pyrolysis a system including some polymer chains and ionic liquids. I know there is ReaxFF which I can use for my polymer, but about ionic liquids, few articles used ReaxFF. My question is, how do I know that a specific ReaxFF is suitable for ionic liquids? If I build a simulation box of ionic liquid and then use the ReaxFF for calculating density, is this path permissible for verifying the chosen force field? If it’s not, could you please tell me which parameter I should check for this purpose?
I would be grateful if you could guide me.
Best regards,
Ali
Density is a very insensitive property, so it is not very suitable. Also, for many classical models (and ReaxFF classifies as that, too) the match may not be great anyway.
I would look up studies of the same ionic liquids using other, non-reactive force fields and try to reproduce those simulations and some of their structural data (g(r)s, self-diffusion coefficient, density, viscosity, averaged geometry (e.g. average angles, bond lengths) or possibly also historgrams of their value distributions). When doing this in a consistent way for 2-3 models/force fields and then also correlate to experimental data, you should have a decent assessment of how accurate classical models could/should be.,
Then you can look for ReaxFF parameter sets for molecular systems with similar structural elements and try to compute the same properties and then make an assessment of how well different ReaxFF parameter sets can reproduce the behavior of your compounds.
None of these calculations would need very large systems since you are comparing same with same there should be quite a bit of error cancellation anyway (but keep in mind that ReaxFF will require a shorter timestep, so you need more simulation steps and output data at different intervals), so it would not be too demanding to test multiple force fields and parameter sets.
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Dear Axel,
Thank you for your detailed response. I’ll do as you said.
How did you make the data file for ionic liquids?