Cndo Calculation Of Dipole Moment Derivatives And Infrared Intensities Of Formaldehyde

The complete neglect of differential overlap (CNDO) approximate wavefunctions for formaldehyde have been applied to the calculation of the derivatives of the dipole moment with respect to the symmetry coordinates (∂p/∂Sj). Agreement between the calculated derivatives and the experimental values given by Hisatsune and Eggers for the A1 symmetry species is exceptionally good, permitting an interpretation of the experimental results in terms of electronic distributions in the molecule. The agreement for the B1 and B2 symmetry species is also very good except for the asymmetric in-plane CH bend. However, the theory successfully predicts that charge reorientation for this motion is quite different from that which occurs in the out-of-plane CH bend, so that these motions are represented by CH bond moments of opposite polarity. An analysis is given of the results in terms of derivatives with respect to internal coordinates (∂p/∂rk). Comparison of ∂p/∂rCS values from a series of X2CO molecules (and also with ∂p/∂rcs for X2CS molecules) reveals an interesting trend. An analysis of the various contributions to the calculated ∂p/∂rk values is presented, with an explanation of the calculated results for the out-of-plane bending coordinate ∂p/∂γ.5862585259

Regularities In Calculated Dipole Moment Derivatives Of First Row Diatomic Hydrides

Calculated dipole moment derivatives from CNDO/2 wavefunctions for the first row diatomic hydride (XH) molecules are compared with the derivatives calculated by Cade and Huo from a near Hartree-Fock calculation. In making this comparison, a remarkably simple straight-line relationship is found to exist between these dipole moment derivatives and the atomic members (Zx) of the X atoms. In the CNDO framework, this linear relationship is due to a nearly linear relationship between q1 (the equilibrium charge on each atom in XH) and Zx. Finally, the results from the CNDO/2 and Hartree-Fock calculations of ∂p/∂R are compared with the values from INDO and CNDO/2D calculations. Copyright © 1974 American Institute of Physics.6151779178