Force field of acetic acid: use of CNDO/force calculations

Abstract

The redundancy-free internal valence force field of monomeric acetic acid is evaluated using CNDO/force calculations and least-squares refinement. The initial force field is set up by taking the interaction and bending force constants from CNDO force field and transferring the stretching force constants from the force fields of chemically related molecules. Vibrational frequencies of monomeric CH₃COOH, CH₃COOD, CD₃COOH, and CD₃COOD are used to refine the force constants. The experimental force field thus obtained is found to be reasonable when compared to the force fields of related molecules as well as on the basis of the frequency fits and potential energy distributions.