Hello everyone, I would like to express my gratitude to those who have guided me on this matter. I am currently working with LAMMPS and a reactive force field (ReaxFF) to simulate the burning of methane in the presence of oxygen and nitrogen. My goal is to observe the formation of different chemical species and bonds between carbon and oxygen. However, my simulation output does not show any changes in the compounds within the simulation box. If anyone has expertise in this area, I would greatly appreciate some guidance. Thank you.
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Please upload your input files here, with log/output files if any.
Have you compared the reaction time of the kind of reactions you want to observe to the run time of your simulation?
You mention “burning” that would mean having a flame and very high temperatures. Do you make an effort to model that? Are the ReaxFF parameters you are using suitable for studying the process you are looking into?
Have you noticed the following warning?
WARNING: No fixes with time integration, atoms won't move (../verlet.cpp:60)
… and the fact that your energies don’t fluctuate??
This is not a question of how to use LAMMPS but a question of how to do simulations. That is not the topic for this forum but rather something to discuss with your adviser or supervisor or tutor or senior colleagues.
Just a few pointers with food for thought.
- You are running at a temperature of about 200-300 Kelvin. Does correspond to “something burning”?
- Your system has only 700 atoms. That is pretty small. What can happen spontaneously(!) with so few atoms?
- Your simulation runs for 4000 steps at 0.001 femtosecond timestep. That is a total time of 4 femtoseconds. What can happen spontaneously(!) in 4 femtoseconds?
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ROTFL 
