The applicability of TD-DFT methods to calculations of the electronic absorption spectrum of hexaamminoruthenium(II) in aqueous solution

The nonstationary density functional theory method (time-dependent DFT, TD-DFT) was used to theoretically estimate the frequencies and intensities of absorption bands of the complex hexaamminoruthenium(II) ion in aqueous solution. The spectrum simultaneously contained both valence (ligand-field, LF) transitions and an intense band of charge transfer to the solvent (CTTS). A comparison of the quality of the results obtained with the use of various exchange-correlation functionals was performed. The closest agreement with the experimental absorption spectrum was obtained with the use of the LC-BLYP hybrid functional with exchange potential corrections at large distances.