3 years ago

Assessing GW Approaches for Predicting Core Level Binding Energies

Assessing GW Approaches for Predicting
Core Level Binding Energies
Ramon Costa, Francesc Viñes, Francesc Illas, Michiel J. van Setten
Here we present a systematic study on the performance of different GW approaches: G0W0, G0W0 with linearized quasiparticle equation (lin-G0W0), and quasiparticle self-consistent GW (qsGW), in predicting core level binding energies (CLBEs) on a series of representative molecules comparing to Kohn–Sham (KS) orbital energy-based results. KS orbital energies obtained using the PBE functional are 20–30 eV lower in energy than experimental values obtained from X-ray photoemission spectroscopy (XPS), showing that any Koopmans-like interpretation of KS core level orbitals fails dramatically. Results from qsGW lead to CLBEs that are closer to experimental values from XPS, yet too large. For the qsGW method, the mean absolute error is about 2 eV, an order of magnitude better than plain KS PBE orbital energies and quite close to predictions from ΔSCF calculations with the same functional, which are accurate within ∼1 eV. Smaller errors of ∼0.6 eV are found for qsGW CLBE shifts, again similar to those obtained using ΔSCF PBE. The computationally more affordable G0W0 approximation leads to results less accurate than qsGW, with an error of ∼9 eV for CLBEs and ∼0.9 eV for their shifts. Interestingly, starting G0W0 from PBE0 reduces this error to ∼4 eV with a slight improvement on the shifts as well (∼0.4 eV). The validity of the G0W0 results is however questionable since only linearized quasiparticle equation results can be obtained. The present results pave the way to estimate CLBEs in periodic systems where ΔSCF calculations are not straightforward although further improvement is clearly needed.

Publisher URL: http://dx.doi.org/10.1021/acs.jctc.7b01192

DOI: 10.1021/acs.jctc.7b01192

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.