Advanced

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

Hellgren, Maria LU and von Barth, Ulf LU (2009) In Journal of Chemical Physics 131(4).
Abstract
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.... (More)
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. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
photoexcitation, autoionisation, atom-photon collisions, beryllium, density functional, theory, eigenvalues and eigenfunctions, neon, HF calculations, photoionisation
in
Journal of Chemical Physics
volume
131
issue
4
publisher
American Institute of Physics
external identifiers
  • wos:000268613700011
  • scopus:68249114412
ISSN
0021-9606
DOI
10.1063/1.3179756
language
English
LU publication?
yes
id
c946f0dd-4830-402f-a966-0de2af83c0e4 (old id 1459939)
date added to LUP
2009-08-25 14:30:24
date last changed
2017-04-23 03:39:34
@article{c946f0dd-4830-402f-a966-0de2af83c0e4,
  abstract     = {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.},
  articleno    = {044110},
  author       = {Hellgren, Maria and von Barth, Ulf},
  issn         = {0021-9606},
  keyword      = {photoexcitation,autoionisation,atom-photon collisions,beryllium,density functional,theory,eigenvalues and eigenfunctions,neon,HF calculations,photoionisation},
  language     = {eng},
  number       = {4},
  publisher    = {American Institute of Physics},
  series       = {Journal of Chemical Physics},
  title        = {Exact-exchange kernel of time-dependent density functional theory: Frequency dependence and photoabsorption spectra of atoms},
  url          = {http://dx.doi.org/10.1063/1.3179756},
  volume       = {131},
  year         = {2009},
}