No reaction with fix bond/react option for vitrimers

no_reaction_forum.zip (607.5 KB)
Dear all,

I am trying to implement the reactivity of disulfides bond exchange reactions in vitrimers -with the fix bond/react option- to reproduce the following article : Redirecting

I used LUNAR to create the pre and post reaction templates , and the map. To the best of my knowledge, I verified those files, and they looked correct. So, I think the problem is more likely coming from LAMMPS and my understanding of REACTER.

To work with the simplest and smallest system possible, I didn’t use a cross-linked box, but just a box with 4-afd molecules where I want to swap the S-S bonds in a two-step process.

However, in my simulation, nothing seems to be happening. I tried playing with the cutoff and the probability already - with no luck. I also tried an equilibration phase to make sure that the molecules were close enough to each other to react, but to no avail. Could you shed some light on why that might be? Any tips on how to fix this would be super helpful!

I linked the files of my minimal working example in a file.zip :

  • Map file
  • Pre_reaction_1.lmpmol
  • Post_reaction_1.lmpmol
  • Input for lammps
  • Initial data with molecules
  • Slurm (log file)
  • And the mechanism from the article (image)

I am using LAMMPS (29 Aug 2024 - Update 2).

Thank you very much in advance for your time and support.

I am unable to reproduce your issue on a more recent LAMMPS version (see attached), and am seeing quite frequent bond exchanges due to your very high reaction distance cutoff. Please let me know if upgrading LAMMPS solves your problem.
LAMMPS_12-Jun-2025.out (20.3 KB)

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Also note that you could model this reaction in one step rather than two, which might be more realistic for this type of bond exchange.

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Thank you for your quick reply. Unfortunately, I am still having no reactions with this new version 12June2025. I am now investigating how I am compiling LAMMPS. I will get back to you soon.

I was able to make it work, thank you again! I also tested the one-step approach as you proposed, and both worked.

If anyone encounters a similar issue, what solved it for me was to change my compiling method to a cmake build instead of traditionnal make as well as compile it with gcc/10.2