Hello,
I am simulating thermal degradation of a chemical mixture using ReaxFF forcefield, and I have the following questions:
Hello,
I am simulating thermal degradation of a chemical mixture using ReaxFF forcefield, and I have the following questions:
- Can the gaseous products released during the reaction/simulation be removed from the simulation box, especially when the gas pressure has built up to a predefined value?
at the time and length scales of a typical MD simulation, any expansion significantly enough to make a difference would be equivalent to a massive explosion.
it seems to me that you are trying to understand processes at the atomic level with a macroscopic perspective. that is not likely to work well.
there is the fix evaporate command, which can be used to remove particles from a simulation, but I doubt that is the kind of approach you should be considering.
- In experiment, the reaction is exothermic, so the temperature of the system is supposed to increase continuously as the reaction proceeds. Which thermodynamic ensemble can be used to simulate this experience?
the ensemble is not something you choose but that is a result of your choices. what rate of temperature increase are we talking about here? is this a “local” reaction (e.g. at a surface or within a solid) or is it “distributed” e.g. in a mixture that is being stirred.
whether you should be using a thermostat to couple your system to an external environment (to simulate an equilibrated bulk) is difficult to tell from the outside.
I suggest you discuss this with people familiar with your research, as this has nothing to do with the “mechanics” of using LAMMPS.
as with the previous question, I get the impression that you are trying to look at atomic behavior through the “macroscopic behavior” lens and thus are worrying about time and length scales that are irrelevant.