MULTIVARIATE STATISTICAL INVESTIGATION OF THE EFFECTS OF WAVE-FUNCTION MODIFICATIONS ON THE CALCULATED VIBRATIONAL FREQUENCIES AND INFRAREDINTENSITIES OF CH2F2

Factorial design calculations for the vibrational frequencies and infr ared intensities of CH2F2 are reported. Vibrational frequencies decrea se by about 100 cm(-1) compared with results obtained from Hartree-Foc k wave functions when the second-order Moller-Plesset perturbation is applied. The inclusion of polarization functions increases the stretch ing frequencies by about 100 cm(-1) and the CH2 and CF2 angular vibrat ions by about 50 cm(-1), whereas it lowers the values of the CH stretc hing frequencies. CH2F2 calculated frequencies, which are found to hav e similar factorial design effects, also have optimal calculated resul ts for the same wave function, Principal component projections of theo retical frequency and intensity results are shown to provide accurate graphical representations of how well these results agree with the exp erimental values, The factorial design models and principal component graphs of CH2F2 are found to be very similar to those of CH3F for the calculated frequencies. However, these results are quite different for the calculated infrared intensities. (C) 1997 Elsevier Science B.V.