Molecular excitation energies from time-dependent density functional theory

Abstract The performance of various exchange-correlation functionals is evaluated in the calculation of molecular excitation energies from time-dependent density functional theory. Excitation energies of N 2 and CO are reported, using either the local density approximation (LDA) for exchange and correlation or an orbital functional in the approximation of Krieger, Li and Iafrate. The latter is based on exact exchange plus a correlation contribution in the form suggested by Colle and Salvetti. While the LDA proves to work remarkably well for the lower excited states due to error cancellations, self-interaction-free potentials are essential for a good description of higher lying states.