(purple part of the bar in fig. ). Surprisingly, in the cases of the simulations starting with CH 4 and C 2 H 6 the total biases are smaller than the total biases on the training conditions. However, note that the main difference is in the bias contribution due to the size of the longest chain. In these simulations the hydrogen to carbon ratio is larger, which prevents the growth of very long carbon chains. Without very long carbon chains, the limitation of the KMC simulation for long carbon chains described above does not occur and the KMC predicted carbon chain length is accurate.