Force Field choice for polymeric electrolyte

OpenKIM
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Hello, I am trying to build up an MD simulation for a polymeric electrochemical system.

My molecules are composed of H, Li, C, N, O, F, and S. I tried automatic topology builders (ATB and LigParGen) but Li is not allowed. First question: why? Is that because these tools are designed to use large molecules? Is Lithium just too hard to parametrize in Gromos/OPLSAA?

I built the LAMMPS topology from Avogadro > Packmol > VMD. I would like to find a force field that includes all species: I have queried the OpenKIM database and found this potential, which is essentially a LJ parametrization. Second question: from the dashboard, this does not perform amazingly. Do you think is it a terrible idea to use it for liquid-state electrochemical simulations?

Last question: ideally I would like to simulate polymerization, which occurs on CH2 groups. Thus I wish to have some sort of reactive ff. It looks like this is a serious limitation to my model. From this post I can see how to make use of hybrid ffs. I could use a mix of a “stable” ff for Lithium (how about Li_Zuo_JPCA2020) and a “good” reax-ff (how about ffield.reax.AB). Can you suggest me any strategy?

Thank you

Marco

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Hi Marco,

It would indeed be a terrible idea to use that potential for any realistic simulation involving covalent bonding, so you will have to look for a potential outside of OpenKIM for now. Although this will not satisfy your desire for a reactive force field, it may interest you that we are actively developing support for bonded force fields, with a targeted public release in September or earlier. Then we are much more likely to have models supporting all your species.

Cheers, ilia

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