Normal modes for probing the local solvation environment of nitrate anion during step wise hydration: A theoretical study

► Geometrical parameters at MP2 level are almost equal to that of B3LYP level. ► Interaction energy and its components are varied linearly with size of the cluster. ► Two scaling factors are applied to account the anharmonic nature of vibrations. ► Excellent agreement between calculated and experimental frequencies is observed. ► Molecular level vibrations provide information of the local hydration environment.