Must Kohn-Sham Oscillator Strengths be Accurate at Threshold?

Abstract

The exact ground-state Kohn-Sham(KS) potential for the helium atom is known from accurate wavefunction 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.

7 pages, 7 figures, submitted to J. Chem. Phys

References in corpus (3)

• Excitations in time-dependent density-functional theory
• Time-dependent density functional theory of high excitations: To infinity, and beyond
• The quantum defect: the true measure of time-dependent density-functional results for atoms

Cited by in corpus (5)

• The effect of cusps in time-dependent quantum mechanics
• Linear-response range-separated density-functional theory for atomic photoexcitation and photoionization spectra
• Photoionization and core resonances from range-separated density-functional theory: General formalism and example of the beryllium atom
• Non-existence of Taylor expansion in time due to cusps
• Semiclassical approximations of photoabsorption cross sections beyond the continuum threshold