Communication: X-ray absorption spectra and core-ionization potentials within a core-valence separated coupled cluster framework

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  • Sonia Coriani
  • Henrik Koch, Norwegian University of Science and Technology, Department of Chemistry, Norway

We present a simple scheme to compute X-ray absorption spectra (e.g., near-edge absorption fine structure) and core ionisation energies within coupled cluster linear response theory. The approach exploits the so-called core-valence separation to effectively reduce the excitation space to processes involving at least one core orbital, and it can be easily implemented within any pre-existing coupled cluster code for low energy states. We further develop a perturbation correction that incorporates the effect of the excluded part of the excitation space. The correction is shown to be highly accurate. Test results are presented for a set of molecular systems for which well converged results in full space could be generated at the coupled cluster singles and doubles level of theory only, but the scheme is straightforwardly generalizable to all members of the coupled cluster hierarchy of approximations, including CC3.

Original languageEnglish
Article number181103
JournalJournal of Chemical Physics
Number of pages5
Publication statusPublished - 2015

    Research areas

  • X-ray absorption spectroscopy, Coupled cluster response theory

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