The dielectric constant dependence of absorption intensities and wavenumbers of the fundamental and overtone transitions of stretching vibration of the hydrogen fluoride studied by quantum chemistry calculations

Vibrational potentials and dipole moment functions of HF molecule in solutions have been calculated as a function of dielectric constant by using the self-consistent reaction field (SCRF)/isodensity surface polarized continuum model (IPCM) calculation. We have selected HF molecule as the simplest polar molecule. The wavenumbers and absorption intensities of the fundamental and the first, second and third overtones of H–F stretching mode have been calculated as a function of dielectric constant. The SCRF/IPCM model calculations have revealed that the vibrational potential and dipole moment function of HF molecule vary continuously with a change in the dielectric constant of the solvent. The calculations were carried out at B3LYP/6-311++G(3df,3pd) and CCSD/aug-cc-pVQZ levels. It has also been found that the absorption intensities of the fundamental increase with the increase of the dielectric constant smoothly but those of the first, second and third overtones do not increase continuously. Moreover, the B3LYP and CCSD levels yielded significantly different results in the dependence of absorption intensities on the dielectric constant.