For all the Si sites, the Si-K edge and the corresponding ground-state PDOS were calculated using the CASTEP code and the OptaDOS 30 code. For the relaxation of electronic structures, the planewave basis pseudopotential method was employed as implemented in the CASTEP code, and the exchange-correlation interactions were approximated using GGA-PBE . The cutoff-energy for the plane-wave expansion was set to 500 eV. In the calculation of ELENS/XANES, core-hole effect was considered by generating the pseudopotentials with a full core-hole, and the supercell approach was employed to eliminate the influence of interactions between core-holes . Reflecting the bond distance between Si atoms, supercells with lattice constants larger than 10Å were used for the calculation of the Si-K edge. A k-point density of 0.03Å -1 was used for the calculation of both the Si-K ELNES/XANES and the ground-state PDOS. The transition energy of Si-K ELNES/XANES can be calculated separately based on the total energy difference between the ground-state and excited-state simulations, but for the prediction of the ground-state PDOS in this study, all the spectra were shifted to their spectral onset to be zero. In other words, the prediction was conducted solely based on their spectral features.