The Decomposition Pathways of SF₆ in the Presence of Organic Insulator Vapors

This paper thoroughly investigates the decomposition pathways of SF₆ in the presence of organic insulator vapors by means of high level quantum chemistry calculations with density functional theory. Optimized molecular structures and vibrational frequencies of intermediate products (IM) and transition states (TS) are first reported in this work. Potential energy surface is then investigated with a more sophisticated CCSD method including zero-point energy corrections and the rate constants are calculated with transition state theory. The overall chemical decomposition pathways of SF₆ + PTFE vapor are obtained which are consisted of 17 reactions with TS1–TS17. By analyzing the rate constants, reactions SF + C → S = CF → TS2 → F + SC, SF₃ + C → TS7 → SF₂CF → TS8 → SFCF₂, SF₄ + C → IM3 → TS11 → IM4 → SF₃ + CF and SF₅ + C → IM5 → TS15 → SF₄ + CF are selected as main reactions in SF₆ decomposition. The results are prerequisite to study the non-equilibrium compositions of SF₆ + organic insulator vapor mixtures.