Theoretical simulation of the nine infrared vibrational frequencies of HNO3 in the gas phase and in an argon matrix

The experimental gas-phase infrared frequencies of nitric acid are simulated fairly well by the anharmonic calculations at B3LYP with the basis sets 6-311++(2df,2pd) or 6-311++(3df,3pd). The experimental argon matrix infrared frequencies of the molecule are simulated properly within the framework of polarizable continuum model by the harmonic calculations at B3LYP/6-311++(df,pd). The matrix-induced frequency shifts are simulated satisfactorily by harmonic calculations applying any of the former three basis sets.