On the multiplicity of solutions of force constants obtained from relative raman intensities and on the uniquesolution of force constant

Abstract

The multiplicity of solutions for the force constants obtained using the data of Raman intensities (vibrational) in the zeroth order approximation of the bond polarizability theory for XY 4 ( T d) type molecules and ions is discussed in detail. The use of such data in fixing a unique set of force constants derived from other rigorous calculations based on the isotopic frequency shifts and Coriolis coupling constants is suggested. Numerical computations of the force constants using the observed intensities in the vibrational Raman spectra are reported for some molecules and ions. For the molecules reported here, it is shown that the selection of the proper set of force constants among the four distinct solutions is possible, if one compares the results with those derived from other additional data along with a study of the trend in the values of the force constants for a group of molecules and the corresponding potential energy distribution.