Accurate singlet and triplet excitation energies using the Localized Hartree-Fock Kohn-Sham potential

We assess the accuracy of the LHFX Time-Dependent Density-Functional Theory (TD-DFT) approach, which uses Kohn-Sham orbitals and eigenvalues from the Localized Hartree-Fock (LHF) method and the exchange-only adiabatic local density approximation kernel. We compute 172 singlet and triplet excitation energies of pi -> pi*, n -> pi*, sigma -> pi* and Rydberg character, for organic molecules of different size. We find that the LHFX method, which is free from the Self-Interaction-Error (SIE) and from empirical parameters, outperforms the state-of-the-art hybrid TD-DFT approaches, and provides the same accuracy for all different classes of excitations. The SIE-free Kohn-Sham orbitals can be thus considered as starting point for TD-DFT developments. (C) 2011 Elsevier B.V. All rights reserved.