Development and application of a ReaxFF reactive force field for molecular dynamics of perfluorinatedketones thermal decomposition

To investigate the thermal decomposition of perfluorinatedketones, ReaxFF parameters were optimized by training against QM-derived calculations using Monte Carlo Annealing method. The optimized parameters showed proper descriptions in predicting the geometries, relative reaction energies and bond dissociation curves of perfluorinatedketones. For validating the reliability of ReaxFF parameters, large-scale atomistic molecular dynamics (MD) with 1 ns long simulations were implemented for thermal decomposition of perfluorinatedketones over the temperature range from 300 to 5000 K. Our simulation results suggested that C-C bond cleavages were prior than other bonds in the initial stages of perfluorinatedketones decomposition. Furthermore, kinetic rate constants and product distributions were also obtained from the simulations, and the apparent activation energies (E-a) were predicted to be 40.10 +/- 1.27 and 42.03 +/- 0.81 kcal/mol for C5 and C6 respectively. With regards to gas mixture decomposition, the main products, including CF4, C2F4, C2F6, C3F6, C3F8, C4F8, CO, COF2, CO2, were observed experimentally. Concerning the insulating gas decomposition under the moisture condition, an etchant gas HF was observed as a characteristic product, which supplies new insights for perfluorinatedketones thermal decomposition process.