On the basis set convergence of TD-DFT oscillator strengths: Dinitrophenylhydrazones as a case study

Using a time-dependent density functional theory approach combined to the polarisable continuum model, we have studied the wavelengths and oscillator strengths related to the electronic transitions of two dinitrophenylhydrazones. Both the neutral and the anionic forms of these dyes have been considered. An extended panel of basis sets has been used and it turns out that the convergence of the oscillator strength value requires, for the anionic species, a much more important computational effort. In addition, comparisons with available experimental data have been carried out.