Excitation energies from time-dependent density functional theory with accurate exchange-correlation potentials†

Abstract

We have applied two of our recently developed methods for calculating accurate Kohn–Sham potentials, namely direct optimization of non-interacting kinetic energy of a known electron density and the asymptotic correction of approximate exchange-correlation potentials, to the calculation of excitation energies within time-dependent density functional theory. Our asymptotic correction method is found not to be adequate in improving Rydberg state results, probably because the potential is still affected by the approximate energy functional due to the variational nature of the method. However, Kohn–Sham potentials calculated from coupled cluster singles and doubles densities give excellent results for the He and Be atoms, and consistently much improved results for molecules.