It is generally difficult to achieve a very good agreement between theoretical and experimental spectra for a large and complicated system as Ser 8 H + . The calculated here spectra qualitatively describe intensity distribution in ranges 1000-1800cm -1 and 2900-3500cm -1 . There are, however some particular deviations worth to mention. In experiment there were no significant signals around 2000cm -1 , whereas harmonic and SWS calculations predict some bands in this region. Only SWS spectrum can reproduce large intensities (although with somewhat shifted frequencies) of the sharp lines at about 3350cm -1 in the experiment, which were assigned to N-H and O-H stretchings. However, neither 500 1000 1500 2000 2500 3000 3500 4000