New Form of Molecular Potential Function for Use in Molecular Vibrational Analysis

Abstract

A molecular potential function which takes simple and direct account of intramolecular strains is proposed. The parameters in the function are the conventional bond-stretching and angle-bending force constants and the strain-free magnitudes of the bond lengths and bond angles. The function is applied to the analysis of the vibrations of XY2 molecules with C2v symmetry. Calculations based on the zero-order frequencies of H2O and D2O indicate that a three-parameter function is adequate for these molecules. All molecules studied with the function show a moderate attraction between the end atoms of the molecules, resulting in a decrease in the size of the bond angle from the strain-free value. For compounds of the oxygen family with hydrogen the bond angle at zero strain appears to have a constant value equal to 120°.