Must Kohn-Sham oscillator strengths be accurate at threshold?
The exact ground-state Kohn-Sham (KS) potential for the helium atom is known from accurate wave function calculations of the ground-state density. The threshold for photoabsorption from this potential matches the physical system exactly. By carefully studying its absorption spectrum, we show the answer to the title question is no. To address this problem in detail, we generate a highly accurate simple fit of a two-electron spectrum near the threshold, and apply the method to both the experimental spectrum and that of the exact ground-state Kohn-Sham potential.
Department of Chemistry, University of California, Irvine, California 92697, USA. zenghuiy@uci.edu
Zeng-hui
ZH
Yang
Meta
M
van Faassen
Kieron
K
Burke