Theoretical spectroscopy on K-2, K-1L-1, and L-2 double core hole states of SiX4 (XÂ =Â H, F, Cl, and CH3) molecules

► We have investigated the K-2, K-1L-1, and L-2 double core hole (DCH) states of the SiX4 (X = H, F, Cl, and CH3) molecules using the CASSCF and DFT methods. ► The effect of the substituents (H, F, Cl, and CH3) surrounding the central Si atom is examined. ► The present results illustrate that the DCH electron spectroscopy for K-2, K-1L-1, and L-2 DCH states is useful for the chemical analysis.