Infrared spectra calculated by quantum chemistry with anharmonic corrections: Application to hydrogen-bonded complexes of nitric acid with various bases

Hydrogen-bonded complexes N2·HNO3, OC·HNO3 and H2O·HNO3 have been studied by means of quantum chemistry methods with electron correlation treatment at the MP2 level with two basis sets and in the framework of the density functional method with four basis sets. Their vibrational spectra have been investigated both at the harmonic and anharmonic levels and the results are compared to available experimental data obtained using by matrix isolation infrared spectroscopy. A comparison of the results is made with the scaling factor method. It is shown that anharmonic corrections on the whole spectra give an unprecedented level of accuracy.