Investigation on Insulation Strength and Molecular Structure of Gas Molecules Based on DFT

SF6 has strong greenhouse effect, and the research on the environmental-friendly alternative SF6 gas has attracted extensive attention. In this article, alkanes, halogenated hydrocarbons, and fluorinated hydrocarbons with special groups were selected as the research objects and a nonlinear regression model for predicting insulation strength was established. The microscopic parameters of each gas molecule were calculated by density functional theory. The calculation functional is B3LYP and the basis are 6-31g/6-31g (d). The results show that the insulation strength of gas molecules increases with the number of carbon atoms in the molecule. When the number of carbon atoms is the same, the insulation strength of gas molecules containing unsaturated bonds is higher. The energy of the lowest unoccupied molecule orbit and vertical electron affinity of gas molecules are important parameters to study the insulation strength of gas, but they have a strong collinearity relationship, so only one of them can be choose in establishing the calculation model of the insulation strength of micro parameters by regression analysis. The insulation strength prediction model describes the sample value characteristics of vertical electron affinity through exponential function, and the correlation coefficient ${R}^{{2}}$ is 0.735, which can preliminarily screen SF6 substitute gases.