| Abstract: | The vibrational frequencies of small organic molecules and inorganic ions were predicted both in vacuum and in the liquid phase at the B3LYP/6-311G++(d,p) level of theory, within the harmonic approximation. The solvent effect was introduced as an electrostatic influence of the bulk by means of the integral equation formalism of the polarizable continuum model. The results show that the application of this continuum solvation model can reduce the overall error in the theoretical predictions. In order to improve the quality of the results, two different scaling procedures were applied. The frequencies obtained for the continuum, when compared with vacuum calculations, show a better linear correlation with experimental data, which increases the efficiency of the scaling procedures. A further reduction of the errors is obtained by partitioning the overall set of frequencies according to the nature of the normal modes and the charge of the solutes. The quality of the theoretical predictions, especially for the stretching modes of vibration of nonionic chemical species, is here noteworthy. |
