The predictions of the "6 MD" KMC model can be compared with experimental data. The trends observed by several experimental works are in agreement with the trends observed in Fig. : when the temperature increases, the concentration of H 2 increases and the number and size of longer hydrocarbons increases too. The model presented here can also give interesting insights on the kinetics or the equilibrium value of experimental systems. In Hirai et al. , starting with CH 4 at temperatures above 3,000 K for a pressure of 40 GPa, diamond is observed. In addition, they do not observe dihydrogen in their system and assume that this molecule is absorbed by the stainless steel gasket of their experimental set up. We can compare these observations with our model predictions. In Fig. , when starting a simulation with CH 4 above 3,000 K and at 40 GPa, the "6 MD" KMC model predicts the size of the longest carbon chain and its H:C ratio to be less than 10 and more than 2.25, respectively. These predictions from our model show that a carbon particle with few hydrogen atoms, compato diamond, should not be produced in these conditions. The hydrogen content of the system is probably too high, preventing a growth of a long carbon chain by release of dihydrogen. This would confirm the assumption of Hirai et al. that another mechanism that removes hydrogen from the system is occurring and, without this mechanism, diamond should be not be observed in these conditions. Kraus et al. propose to use shock experiments to avoid the problems due to the reactions with other parts of the diamond anvil cell. In a shock experiment, the temperature and the pressure are increased on short timescales (on the order of a few nanoseconds), resulting in a system where the hydrocarbon mix does not have sufficient time to react with the other part of the diamond anvil cell. With this setup, Kraus et al. do not observe diamond at 50 GPa and 2,800 K starting from polystyrene ((C 8 H 8 ) n ). However, the kinetics and mechanism of diamond formation are poorly understood and, to our knowledge, there is no evidence that a few nanoseconds is enough time for diamond formation under these conditions. Our model can make these predictions, assuming that the behavior of the system at 50 GPa is similar to the behavior at 40 GPa and that the time for equilibrium negligibly depends of the hydrogen content of the initial system. In Fig. , we can observe that at 2,800 K the system needs around 1-10 ns to come to equilibrium with a system starting with CH 4 or with C 4 H 10 , which is the same order of magnitude as the experiments run by Kraus et al. Therefore, our model points out that Kraus et al's experiments are on timescales close to the time needed for equilibrium to be reached. It is important to notice that our model is fit on the ReaxFF potential, but ReaxFF has been shown to sometimes fail to reproduce ab initio energies and some common reactions are not observed in ReaxFF simulations .