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 N2 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. (C) 2000 Elsevier Science B.V.
Bibliographical noteFunding Information:
We thank D. Sundholm and P. Pyykkö for providing us with their two-dimensional Xα code for molecules  . This work was supported by the Deutsche Forschungsgemeinschaft.
- Local density approximation
- Molecular excitation energies
- Time-dependent density functional theory