Performance of ab initio and DFT PCM methods in calculating vibrational spectra in solution: Formaldehyde in acetonitrile as a test case

We report the anharmonic spectra calculated for formaldehyde in acetonitrile solution using quartic force fields obtained at different levels of theory in connection with the SCI-PCM continuum solvent model. The fair agreement observed with the experimental data and with the observed shifts relative to the gas phase shows that the CCSD(T)/cc-pVQZ/SCIPCM and the hybrid CCSD(T)/cc-pVTZ//B3LYP/6-31+G(d,p)/SCIPCM approaches can be recommended to calculate reliable vibrational spectra in solution for medium size systems.