To conclude, the electronic structure and nuclear dynamics of SF 6 molecule have been investigated by F 1s XA and RIXS spectroscopy and analyzed using firstprinciple electronic calculations accompanied by the wave packet simulations of the nuclear dynamics. In the simulations, we employ two levels of quantum chemical methods: TD-DFT/CAM-B3LYP and DFT-ROCIS/B3LYP. Due to the strong degeneracy of the F 1s core shell in SF 6 , the vibronic coupling results in a localization of the core-hole in the F atom. The core-hole localization re- : Role of the nuclear dynamics. Experimental and calculated quasi-elastic RIXS bands for horizontal (red) and vertical (blue) photon polarization along with experimental spectrum obtained from Ref. . Mid and lower panels compare total theoretical RIXS profile with and without taking into account the nuclear dynamics, respectively. The peaks corresponding to |4t -1 1u 6a 1 1g > and |5a -1 1g 6a 1 1g > are not present in the dynamical spectra, as those states could not be diabatized properly and are hence omitted from simulations. The static spectrum is convoluted by a constant Gaussian broadening whereas the broadening in the dynamical spectra results from the wave packet dynamics.