The soot formation process is investigated with our NN potential. Two kinds of systems are studied: acetylene for their polymerization and the formation of aromatic rings and PAH π-radicals and σ-radicals for physically stabilized soot inception. Figure shows the structure of the PAH radicals studied in this work. PAH-a, -c, and -e are σ-radicals involved in soot inception, while PAH-b, -d, -f, and -g are π-radicals reported in simulations and experiments . Before MD simulations, monomers of acetylene and PAH radicals were optimized using the DFT method with the B3LYP/6-311G(d,p) level of theory. The optimized monomers were duplicated 1000 times for acetylene and 50 for PAH radicals and then randomly distributed in a cubic box. The equations of motion are integrated by the velocity Verlet method using periodic boundary conditions. A Nose-Hoover thermostat is applied with an equilibrium temperature of 1500 K and a dump parameter of 20 fs. A one ns MD simulation with a time step of 0.l fs is performed for both acetylene and PAH radical systems. The nanoreactor method is used to accelerate the simulation, where a virtual piston in a sphere is imposed on the system during MD simulations. The virtual piston is defined by a time-dependent boundary potential where k=0.01 kcal mol -1 Å, τ = 1.0 ps, T = 2.0 ps.r0 is the sphere radius, m is the atomic mass, ⌊ ⌋ is the floor function and θ is the Heaviside step function. To minimize the temperature fluctuations in nanoreactors, the compression process is divided into three stages.