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Exact-exchange kernel of time-dependent density functional theory: Frequency dependence and photoabsorption spectra of atoms

Journal Article · · Journal of Chemical Physics
DOI:https://doi.org/10.1063/1.3179756· OSTI ID:21559742
;  [1]
  1. Department of Mathematical Physics, Institute of Physics, Lund University, Soelvegatan 14A, S-22362 Lund (Sweden)
In this work we have calculated excitation energies and photoionization cross sections of Be and Ne in the exact-exchange (EXX) approximation of time-dependent density functional theory (TDDFT). The main focus has been on the frequency dependence of the EXX kernel and on how it affects the spectrum as compared to the corresponding adiabatic approximation. We show that for some discrete excitation energies the frequency dependence is essential to reproduce the results of time-dependent Hartree-Fock theory. Unfortunately, we have found that the EXX approximation breaks down completely at higher energies, producing a response function with the wrong analytic structure and making inner-shell excitations disappear from the calculated spectra. We have traced this failure to the existence of vanishing eigenvalues of the Kohn-Sham non-interacting response function. Based on the adiabatic TDDFT formalism we propose a new way of deriving the Fano parameters of autoionizing resonances.
OSTI ID:
21559742
Journal Information:
Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 4 Vol. 131; ISSN JCPSA6; ISSN 0021-9606
Country of Publication:
United States
Language:
English