Methane example polymerizes nitrogen

[mliu49]

The methane example has nitrogen as a reactive species, so it ends up creating species like N(=NN=[N])N=NN=NN=[N] and N([N]N=NN=[N])(N=NN=NN=NN=[N])N=[N].

If nitrogen was intentionally set as a reactive species, then we probably need to set a species constraint on the maximum number of nitrogen atoms.

[KEHANG]

Okay, thanks! Will add a constraint of maximumNitrogenAtoms = 2 there. @alongd, and @nyee do you guys have any suggestions on the constraint for nitrogen?

[alongd]

The methane example has only GRI as a seed library (not the GRI-N version), and no other libraries to help RMG with small radical reactions of nitrogen. So I think it will make sense to make N2 a non reactive species here. Alternatively, we could use the GRI-Mech3.0-N library if we do want N chemistry, and then I would also recommend to restrict maxNatoms to 2 (capture NO, NO2, N2O, N, NH...)

[KEHANG]

thanks, @alongd!