  Incipient soot particles obtained from a series of reactive molecular
dynamics simulations were studied to understand the evolution of physical,
chemical, and morphological properties of incipient soot. Reactive molecular
dynamics simulations of acetylene pyrolysis were performed using ReaxFF
potential at 1350, 1500, 1650, and 1800 K. A total of 3324 incipient soot
particles were extracted from the simulations at various stages of development.
Features such as the number of carbon and hydrogen atoms, number of ring
structures, mass, C/H ratio, radius of gyration, surface area, volume, atomic
fractal dimension, and density were calculated for each particle. The
calculated values of density and C/H ratio matched well with experimental
values reported in the literature. Based on the calculated features, the
particles were classified in two types: type 1 and type 2 particles. It was
found that type 1 particles show significant morphological evolution while type
2 particles undergo chemical restructuring without any significant
morphological change. The particle volume was found to be well-correlated with
the number of carbon atoms in both type 1 and type 2 particle, whereas surface
area was found to be correlated with the number of carbon atoms only for type 1
particles. A correlation matrix comparing the level of correlation between any
two features for both type 1 and type 2 particle was created. Finally, based on
the calculated statistics, a set of correlations among various physical and
morphological parameters of incipient soot was proposed.
