The geometry of SF 6 was optimized using the M06-2X hybrid functional in the Gaussian-16 program package , which is known to perform well in predicting structures of main group element compounds . All calculations were performed with the def2-TZVP basis set . The optimized geometry has O h symmetry with a S-F bond distance of 1.559 Å, against the experimental value of 1.561 Å, and sing DFT computation we obtained Kohn-Sham orbitals relevant for in the XA, XE and RIXS processes. The orbital, classified into irreducible representations (IRREPS), are shown in FIG. and FIG. , and S3 in the supplementary information (SI).