Identifying molecules with high electrical strength

Abstract

A search is conducted for possible gases with high electrical strength which could replace the widely used SF6 which has high global warming potential (GWP). The possible electrical strength of a molecule is assessed on the basis of low-energy electron collisions with low-energy resonances or weakly bound states taken as a possible indicator of high electrical strength. At the same time the energy of the highest occupied molecular orbital (HOMO) is used to assess the molecules’ GWP. A total of 62 small flourocarbon molecules are considered allowing the influence of different molecular structures (double bonded, triple bonded and cyclic) and the inclusion of different elements (hydrogen, nitrogen and oxygen) on the electrical strength to be assessed. Eight molecules show low-energy resonance and a further four have negative R-matrix poles implying that they support an anionic state. Our calculations suggest that molecules with double bonded structures, especially involving C = N, should have the best electrical strength, followed by cyclic and then triple bonded structures. Calculation on the C3F6−n H n (n = 0, 6) series suggest that introducing H atoms in selected positions can decrease GWP while retaining the electrical strength of pure fluorocarbon gases like C3F6.