Knowledge Bank

Normal vibration calculations of acetic acid monomer $(CH3COOH,CH3COOD,CD3COOH,CD3COOD)$ and acetic acid dimer $((CH3COOH)2,(CH3COOD)2,(CD3COOH)2$ and $(CD3COOD)2)$ were carried out using Urey-Bradley force field with correction terms. On the basis of the experimental assignments of vibrational spectra of spectra of acetic acid monomer and dimer so far published and also on the basis of the calculated frequencies and the potential energy distributions, a correspondence was set up between the observed frequencies and the calculated frequencies. Force constants were adjusted by a perturbation procedure so as to give a satisfactory agreement of the observed frequencies with the calculated frequencies in the correspondence, and the nature of vibrations was elucidated by the potential energy distributions calculated using the final set of force constants.