Assessing GW approaches for predicting core level binding energies
(2018) Journal of Chemical Theory and Computation — Vol. 14, n° 2, p. 877-883 (2018)
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- Abstract
- Here we present a systematic study on the performance of different GW approaches: G0W0, G0W0 with linearized quasi particle 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 ∆SCF 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 ∆SCF 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 quasi particle equation results can be obtained. The present results pave the way to estimate CLBEs in periodic systems where ∆SCF calculations are not straightforward although further improvement is clearly needed.
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van Setten, M., Costa, R., Viñes, F., & Illas, F. (2018). Assessing GW approaches for predicting core level binding energies. Journal of Chemical Theory and Computation, 14(2), 877-883. https://doi.org/10.1021/acs.jctc.7b01192 (Original work published 2018)