Abstract
An approximate solution to the time-dependent density-functional theory response equations for finite systems is developed, yielding corrections to the single-pole approximation. These explain why allowed Kohn-Sham transition frequencies and oscillator strengths are usually good approximations to the true values, and why sometimes they are not. The approximation yields simple expressions for Görling-Levy perturbation theory results, and a method for estimating expectation values of the unknown exchange-correlation kernel.
- Received 28 February 2002
DOI:https://doi.org/10.1103/PhysRevLett.90.043005
©2003 American Physical Society
