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 C_2v 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°.