Accurate Absolute and Relative Core-Level Binding Energies from GW

Area of Science:

• Computational Physics
• Quantum Chemistry
• Spectroscopy

Background:

• Green's function (GW) methods are widely used for electronic excitations.
• Core-level spectroscopy calculations remain challenging within standard GW approximations.
• Density functional theory (DFT) methods have limitations for core-level spectra.

Purpose of the Study:

• To develop an accurate GW-based method for computing X-ray photoelectron spectra (XPS).
• To address the shortcomings of common DFT approaches for core-level binding energies.
• To establish a reliable computational tool for core-level spectroscopy.

Main Methods:

• Application of the GW Green's function method for core-level excitations.
• Investigation of single-shot perturbation calculations (G0W0) and their limitations.
• Implementation of partial self-consistent GW schemes and hybrid functionals.
• Inclusion of relativistic corrections.
• Benchmark study of 65 molecular 1s excitations.

Main Results:

• Standard G0W0 calculations inaccurately transfer spectral weight for core levels.
• Partial self-consistent GW or hybrid functionals as starting points restore correct spectral behavior.
• Absolute and relative GW core-level binding energies show excellent agreement with experimental data (within 0.3 and 0.2 eV, respectively).

Conclusions:

• The proposed GW approach accurately computes core-level X-ray photoelectron spectra.
• This method overcomes limitations of standard DFT and G0W0 approximations for core-level spectroscopy.
• The findings pave the way for more reliable theoretical predictions in core-level spectroscopy.