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

We have investigated the K (2), K L-1 (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 aiming at the DCH electron spectroscopy. The Si 1s IPs and DIPs of the present molecules and the generalized relaxation energies are compared and analyzed. The values extracted from the excess relaxation energy agree well with the generalized relaxation energy. 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. (C) 2011 Elsevier B.V. All rights reserved.