Study on Pyrolysis Characteristics of SF6 in a Trace-Oxygen (O2) Environment: ReaxFFSFO Force Field Optimization and Reactive Molecular Dynamics Simulation

The ReaxFF SFO force field for a SF 6 -O 2 system is developed based on the density functional theory (DFT) calculation data. Then, a series of molecular dynamics (MD) simulations were performed. The results show that the main oxygen-containing compounds that appeared in the MD simulation include SOF 4 , SOF 2 , and SO 2 F 2 . The relative quantitative relationship between SOF 2 and SOF 4 can be used to determine the fault temperature. Besides, under overheating conditions, O 2 rarely undergoes a self-cracking process to generate free O atoms. Instead, the basic route for O 2 to participate in the SF 6 pyrolysis process is X + Y + O 2 = XO + YO. Furthermore, the reactivity order of various groups to O 2 is (SF 2 )* > (SF 3 )* > (SF 4 )* > F*, so O 2 is more likely to participate in the reaction by attacking (SF 3 )* or (SF 2 )* groups. This study laid the foundation for the application of ReaxFF MD simulations to study the microscopic dynamic mechanism of SF 6 pyrolysis in more complex systems.