title: First-Principles Investigation of Strong Excitonic Effects in Oxygen 1s X-ray Absorption Spectra.
abstract: We calculated the oxygen 1s X-ray absorption spectra (XAS) of acetone and acetic acid molecules in vacuum by utilizing the first-principles GW+Bethe-Salpeter method with an all-electron mixed basis. The calculated excitation energies show good agreement with the available experimental data without an artificial shift. The remaining error, which is less than 1% or 2-5 eV, is a significant improvement from those of time-dependent (TD) density functional methods (5% error or 27-29 eV for TD-LDA and 2.4-2.8% error or 13-15 eV for TD-B3LYP). Our method reproduces the first and second isolated peaks and broad peaks at higher photon energies, corresponding to Rydberg excitations. We observed a failure of the one-particle picture (or independent particle approximation) from our assignment of the five lowest exciton peaks and significant excitonic or state-hybridization effects inherent in the core electron excitations.
authors.affiliation: Institute for Solid State Physics, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Noguchi
authors.affiliation: Institute for Solid State Physics, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Miyabi
authors.initials: M
authors.lastname: Hiyama
authors.affiliation: Institute for Solid State Physics, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Akiyama
authors.affiliation: Institute for Solid State Physics, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Harada
authors.affiliation: Graduate School of Information Science, Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Koga