Density functional computations of the dipole moment derivatives for halogenated silanes

Electric dipole moments for the equilibrium molecular structures and their derivatives along the symmetry coordinates of vibration were computed for SiH2F2, SiD2F2, SiH2Cl2, SiD2Cl2, SiH3F, SiD3F, SiH3Cl, SiD3Cl, SiHF3, SiDF3, SiHCl3, SiDCl3, SIFCl3, SiF3Cl, SiF4 and SiCl4 by means of the deMon density functional program (A. St-Amant and D. R. Salahub, Chem. Phys. Lett., 169 (1990) 387). Satisfactory agreement was found between the experimental and computed dipole moments for the equilibrium molecular structures. Perfect agreement was found between the rotational corrections to the dipole moment derivatives calculated by deMon and those obtained independently from the orthogonality relationships between the symmetry coordinates and the rotational coordinates. Derivatives of the dipole moments were transformed into the representation of the normal coordinates of vibration and the results were compared with the experimental data which are available on the infrared intensities of fundamental bands.