Characteristic Substitution Shift Model (CSSM) in the CCFDF (Charge-Charge Flux-Dipole Flux) model for the dipole moment derivatives of molecules X2CY (X = F, cl; Y = O, S)

Abstract

In the spectroscopic study of the X2CY molecules, the dipole moment derivative model Charge – Charge Flux - Dipole Flux (CCFDF) derived from the QTAIM theory was used to verify if the CSSM (Characteristic Substitute Shift Model) model was adequate to represent the derivatives of the dipole moment of the X2CY molecules. To choose the best level/basis combination, a study varying level electron correlation with different basis set was performed to see which wavefunction best describes the dipole moment of the X2CY molecules. When the derivatives of the dipole moment CCFDF are decomposed into charge, charge flux and dipole flux, the CSSM model perfectly represented the charge component, however, it presented small discrepancies for the charge flux and more significant discrepancies with respect to the dipole flux, due to the difficulty of this model representing the variations of the atomic dipole of the sulfur atom.