Multidimensional coupled structure-activity relationship models for replacement of SF6

Abstract

Computational screening of single gases to replace SF₆ for electrical insulation has been challenged by the difficulty in combining various mutually exclusive properties especially for dielectric performance with liquefaction and environmental properties. To reveal the inherent correlations between dielectric strength (E_r), boiling point (T_b), and global warming potential (GWP) of dielectric materials, a coupled structure-activity relationship (CSAR) model has been proposed for the first time. By means of the generic descriptors, as deduced from the electrostatic potentials, and the specific descriptors, as introduced from the respective microscopic mechanisms, the complex interdependence between E_r, T_b, and GWP of the insulation gases is quantitatively characterised by the 3-D coupling matrix. The coupling mechanism for the right balance of properties is uncovered in terms of the first-principle descriptors. The CSAR model outperforms the previous SAR models in predicting E_r, T_b, and GWP simultaneously in a self-consistent manner. More importantly, the concept of CSAR could be extended readily to any multidimensional macroscopic properties. Novel replacement compounds have been identified tentatively to be the promising candidates to replace SF₆ using the CSAR model.